Category: The Company

Vulcan would have never endured as long as it did without a properly engineered product, especially in the punishing environment of impact pile driving equipment. There is a great deal of technical information on this site; here we give a glimpse as to how much of it came into being. There are special sections on CAD, Finite Element Analysis, and Numerical Analysis.

The first extant layout of the Vulcan #2 Hammer, dated 9 February 1887. It’s probably the first extant layout of the Warrington-Vulcan hammer. Until about World War I, it was common practice for Vulcan to lay out the general arrangement and then the shop produce the hammer from just that drawing. It’s an indication of both the skill and the decision making ability of those actually producing the product, and also probably of the involvement of those doing the design work.

Once the hammer was designed, leaders were necessary. This set of leaders is dated 11 April 1889 for O.H. Ernst, Major of Engineers, Galveston. As was the case for many years, this set was made out of wood. Leaders were made for both drop hammers and steam hammers. Other designs can be seen in our catalogue review. In the early years of the product line, American pile driving equipment of all kinds was generally run on a “dedicated” rig, i.e. one which was only used for pile driving. The practice of using a multi-purpose crane became standard around World War II. The dedicated rig remained popular outside the U.S. and has made recent inroads in the American market.

Any pile driving rig needs a “prime mover.” Many smaller ones used human or (more commonly) animal power. Vulcan built its reputation on steam driven equipment, and produced steam engines for some of its pile driving rigs. One of those is shown below. Note the rotary Corliss valve at the top of the drawing. This is the same type of valve that was used in the Warrington-Vulcan hammers and every other Vulcan hammer except for the #5, California series hammers, pile extractors and the Single-Compound hammer (the last two were valveless.)

the design of the valve, trip (cam) system and the steam chest was at the heart of every Vulcan hammer. Below is a layout of the “00” hammer dated 16 January 1912. Unfortunately that hammer size didn’t quite get off of the ground, and Vulcan would wait nearly twenty years before producing a hammer of that size.

Another, more elaborate view of a steam engine, here a pile driver hoisting engine, dating from 1903.

Vulcan’s reciprocating steam engines weren’t only used on pile driving rigs. In the same era Vulcan was also heavily involved in building dredges. We have a complete page on the subject; we’ll concentrate here on some of the design engineering aspects of those vessels.

A “strain sheet” for a truss design for the #3 dredge dated 20 February 1889. Using a combination of graphical and analytical techniques, the stresses and displacements in the truss are computed.

Another strain sheet, this time for the dipper friction, done by George Warrington and dated 22 April 1893.

From the beginning of the Warrington-Vulcan product line (and presumably earlier) until the 1950’s Vulcan drawings were largely drawn in India ink on linen. They were thus durable and reproduced well, and (as is evident here) have some artistic value. Unfortunately they were hard to change, but given the static quality of Vulcan’s product line that wasn’t as big of a disadvantage as one might think.

Although it’s hard to read, a “stress and force” diagram for leaders. The analysis of statics was well established in engineering education and practice by the last half of the nineteenth century and is employed in this case on pile hammer leaders. In this case the leaders are being analysed using a truss type of model and a graphical solution to the static equilibrium equations. Truss models are, strictly speaking, inapplicable to leaders, because the joints are not pinned, but can be a reasonable approximation. The labour of calculations pushed the industry towards a more “section modulus” approach (which has limitations of its own) but the best solution to date has been finite element analysis, which will be discussed below.

Another analysis with a more contemporary urgency is overturning of the rig. Below is an overturning analysis for a swivelling pile driver. Whether the rig is an old Vulcan rig, conventional crane rig, dedicated pile driving rig or an excavator mast mounted hammer, preventing overturning is essential.

Not all drawings were for sold product. Below is a diagram for modifying a planer to make a machine that would cut the cam on the ram of a DGH-900 hammer, from 1958. Today operations like this would be programmed into CNC machinery, but at the time the skill and ingenuity of the tool and die maker were applied to the task.

Between the World Wars Vulcan’s proficiency in ink and linen reached its height. Below is a general arrangement for the 1800 closed type hammer, drawn in 1931.

The hammers needed design and drawings, and so did the packaging. Below is an export box for the Vulcan #1 hammer. Vulcan was engaged in international commerce from the earliest days of the product line. Sometimes that was generated by American companies working overseas and sometimes by foreign concerns. For domestic shipment Vulcan usually mounted its hammers on skids, either wooden or steel. In more recent times the hammer was simply chained to the flatbed. For offshore hammers a steel skid was necessary, and the hammer was shipped as deck cargo.

Towards the end of the 1950’s Vulcan made two important changes in the way it made drawings: it went to pencil drawings and it drew them on vellum, which was preprinted with standard borders and title blocks. Additionally, after the move to Chattanooga it mandated the use of lettering templates. All of these resulted in drawings that were easy to change and had a more uniform look about them, but did not have the visual appeal of their earlier counterparts. Also, the vellum tended to fray with repeated reproduction; Vulcan’s reproduction machines used a contact process with ammonia development, which made the office stink, especially with poor ventilation. This forced frequently used drawings to have to be redrawn frequently.

Vulcan rectified many of the weaknesses of the pencil/vellum system around 1970 with two changes: it went to mylar drawings, which were expensive but lasted longer, and went from a plain graphite pencil to a “grease” pencil for darker lines and better reproduction. A nice example of this is the general arrangement of the 520 hammer, shown below, from 1982.

From 1967 to 1984 Vulcan had two engineering facilities: Chattanooga and West Palm Beach. Below is a sample of the latter’s output, which reflected its mission as a fabricating facility, primarily for Vulcan’s offshore leaders.

When it was time to go “back to the drawing board” at the Special Products Division, this is where they went: part of the engineering section of the Division, July 1974.

Below is an example of one of these, a layout of an ocean pile hammer from the late 1960’s.

The drawing board(s) in Chattanooga. On the wall are sheet pile sections, cut from actual sheet piling and used to lay out sheet pile caps. In front of the sheet piling are two draughtsmen who started at Vulcan in the early 1970’s. On the left is Michael Steven Alexander, who worked for Vulcan until he left during the downturn in the first part of the 1980’s. On the right is William C. Harrison, who went off the board to become Vulcan’s Field Service Representative in 1981.

Computer Aided Design (CAD)

By the mid-1980’s CAD was becoming a viable option for companies the size of Vulcan. In 1986 Vulcan purchased its first personal computer (PC) for the purpose, but the original software was unworkable, so Vulcan purchased DesignCAD and began producing drawings by computer drafting. The first hammer to be principally designed by CAD was the Vulcan 1400 vibratory hammer.

A screen shot from DesignCAD 4 for DOS, showing the hydraulic schematic for the Vulcan 2800 vibratory hammer. Given the limitations of DOS and the computers they ran on, the results that DesignCAD produced were amazing. Additionally DesignCAD did fine with just a keyboard, a mouse and a standard graphics card, obviating the need for additional hardware such as digitising pads.

By 1990 hand drawing (except for changes) was pretty much a thing of the past. Below is the general arrangement of the Vulcan 5110 hammer, the last new model to be placed into production by the Vulcan Iron Works.

Other examples of Vulcan’s CAD output can be found in our page on the “last hammers.”

Finite Element Analysis (FEA)

While Vulcan’s competitors such as HBM trumpted their use of FEA for designing hammer components, Vulcan got its start in 1977 with the analysis of the 6250 pipe cap, which was being proposed to McDermott. The analyses were conducted by Dr. William Q. Gurley at the University of Tennessee at Chattanooga, who was later involved in this effort.

Element grid for the Vulcan 6250 pipe cap.

Displacement Diagram for the 6250 pipe cap.

Maximum shear stress diagram for the 6250 pipe cap.

Finite element analysis was revived in the 1990’s for the analysis of the leaders. Below is a sample of that effort, from 1996. In both cases the ANSYS software package was used.

Vulcan went on to analyse the 6300 pipe cap when McDermott “upsized” the hammer. Vulcan also conducted analyses on other hammer size pipe caps and piston rods as well; the former led to lightening the pipe caps considerably.

Numerical Analysis

For most of its history Vulcan used “closed form” solutions to predict the cycle behaviour of its hammers. In the early 1980’s, however, Vulcan developed the capability to analyse a hammer cycle using numerical methods and flow prediction, including valve losses. The first hammer to use this type of analysis in the actual original design of the hammer was the Single-Compound Hammer, where the complexities of the flow made such an analysis almost mandatory.

Vulcan’s most ambitious numerical analysis project was the ZWAVE wave equation program. That, in turn, was a prelude to projects beyond Vulcan, namely those of the closed form solution for the wave equation and the FEA solution of the wave equation, forward and inverse.

Vulcan had a long and interesting history. Some of that is documented below:

• Vulcan: The First 100 Years
  • A history in words and photos of Vulcan’s first century of existence
  • Vulcan Iron Works Centennial Celebration
• Vulcan: The Offshore Experience
  • A comprehensive view of Vulcan and its offshore hammers
• Product Bulletins: a list of the literature Vulcan put out to explain the products and the company, and an excellent overview of the products that Vulcan made.
• Engineering at Vulcan, a tour of Vulcan’s engineering output, from ink and linen drawings to CAD and finite element analysis
• Experimental and “Vapourware” Products
  • Internal Pile Hammer IPH-16, Vulcan’s attempt to revolutionise steam hammers offshore.
  • Single-Compound Hammer, an air/steam hammer even simpler than the original.
  • Construction Assistance Vehicle (CAV,) an underwater craft built for the U.S. Navy.
  • “The Last Hammers:” a sampling of some of the air/steam and vibratory hammers Vulcan Iron Works designed but did not produce in its last years.
  • Special Products Division: the source of many of Vulcan’s “one of a kind” products
  • Concrete Pile Cutter: an interesting Russian concept
  • Russian Diesel Hammers: another interesting Russian concept
  • Sea Water Hammer: the daring concept that was Vulcan’s last patent
• Corporate Matters: Vulcan dealt with a variety of corporate and financial matters that were unusual for an organisation of its size. Some of these were as follows:
  • Letters of Credit, essential for its international business activities
  • Caldwell Steam Snow Plough, which ended up putting Vulcan into the case law of replevin
  • The “Turkey Grievance,” an example of the procedures for resolving conflicts in organised labour relations
• Vulcan Patents — a century and more of technological history
• Vulcan Serial Numbers — wonder how old that Vulcan hammer of yours is?
• Nilens — Vulcan’s licensee in Europe, and the producer of its first marketable line of diesel hammers
• Conmaco: the Kansas City based equipment distributor turned competitor who, in the end, helped to propagate the Vulcan style hammer.
• Design and Performance of an Electro-Pneumatic Pile Hammer for Laboratory Applications.–when academics find out that equipment design isn’t as easy as it looks. Vulcan assisted with this research.

Need further information? Click here to contact us.

Vulcan was an innovator in pile driving equipment for more than a century. This history can be documented in part by the patents that were issued to Vulcan’s people, in addition to those which it acquired externally. We also include patents that were related to Vulcan either because they were issued to a Warrington or they related to a Vulcan product but were never formally assigned to the company.

We also have experience in acting as an expert witness in patent disputes; contact us if you are interested.

Vulcan’s success in its product lines inspired imitators.  One of the most significant of those came from its own distributor network—Conmaco.  The relationship between the two companies was as complicated of a business as one could want, both together and apart.

Conmaco was started in 1910 as Contractors Machinery Company.  Three years later Scott Myers, whose family came to become principals in the business, became associated with the company.  In 1938 Vulcan and Conmaco signed their first distributor’s agreement in which the Kansas City, Missouri based business became Vulcan’s dealer in western Missouri and the entire state of Kansas.

While Vulcan’s future principal was off fighting World War II, the companies had their first falling out.  In the spring of 1944 the Bureau of Yards and Docks sent out a bid to Conmaco for 254 drop hammers.  Vulcan was only capable of delivering 112 of these by the end of the year, so Conmaco proposed that it produce the balance of the order itself.  In good company tradition, Vulcan’s Secretary-Treasurer, Walter Daspit, flatly turned down Conmaco’s request.  (William H. Warrington had set the precedent for this with Raymond before World War I.)  On 20 May 1944, as the Allies celebrated taking the remains of the Monte Cassino monastery, Conmaco cancelled their distributor’s agreement with Vulcan, which Daspit accepted without any attempt at settlement.

The end of World War II also brought reconciliation between Vulcan and Conmaco.  On 7 September 1945, five days after the Japanese surrendered to the Allies on the deck of the Missouri, Vulcan formally reinstated their Missouri-based dealer.

As the country’s economy shifted from wartime to peacetime, Conmaco pursued the capabilities it first explored during the war by either producing its own drop hammers or reselling those purchased at surplus.  As early as 1949 Vulcan queried Conmaco on this matter.  Nevertheless in the mid-1950’s Conmaco was generally Vulcan’s most important distributor.  In September 1957 Vulcan and Conmaco (which had formally changed its name and moved to Kansas City, Kansas) signed a new distributor agreement.

Although Conmaco continued to be an important distributor and its territory expanded to other Midwestern states, the relationship progressively deteriorated during the first half of the 1960’s.  Part of the problem was that the nature of the market was changing.  Up until that time Vulcan had an extensive network of distributors which dealt in a wide variety of construction related products.  Pile driving equipment is a specialized product in a specialized market, and “general equipment” distributors (even in some cases crane dealers, for whom pile driving equipment was a natural adjunct product) were losing interest in the product.  Things were further complicated by the emergence of a rental market for the hammers.  Vulcan’s entire marketing strategy was based on hammer sales; rentals (which made sense for infrequent users and joint ventures) cut into that.  Conmaco responded to both of these trends by concentrating on the pile driving equipment (along with other related products such as winches and cranes) and developing a rental fleet.  This last was not to Vulcan’s taste, although it was a market trend that ultimately Vulcan could do nothing about (and having as durable of a product as it had only accelerated the trend.)

Additionally, Conmaco continued to develop its own production capabilities of driving accessories, leaders and producing Vulcan hammer parts.  This basically turned Conmaco into a competitor to Vulcan.

Things came to a head in January 1965 when Vulcan cancelled its distributor’s agreement with Conmaco.  The situation was further complicated by the fact that Conmaco had hired Vulcan’s Vice President of Sales, Earle R. Evans, in February 1965.  (Evans had been involved in the coming of Prince Alexandre de Rethy of Belgium to Palm Beach the previous month.)  In spite of all of this the two companies remained in dialogue, so Vulcan continued to treat Conmaco as a distributor; however, there was no formal agreement until early the following year.

The two organisations spent the rest of the decade trying to maintain a relationship.  At one point Conmaco even had their Chicago branch at Vulcan’s old facility at 327 North Bell.  In 1967 Vulcan drew up and produced to Conmaco’s specifications the Conmaco 200 hammer, a counterpart to Vulcan’s 020.  There were many detail changes, but the most significant was that the hammer was tied together with a cable wrap system designed by Dwayne Smith, Conmaco’s Equipment Manager.

The cable wrap system was a mixed business.  One the one hand, the wrap system is labour-intensive and requires the hammer to have larger jaws (and thus require larger leaders) than the system that Raymond developed and Vulcan adopted for its own hammers.  On the other hand the larger jaws made it simpler to accommodate larger piling, which is especially advantageous with hammers in the 300E5 range. Additionally the smaller Conmaco hammers sported cables of kind before their Vulcan counterparts did.

Vulcan went on to produce the Conmaco 140 and 160 hammers (counterparts to Vulcan’s 014 and 016 sizes.)  But time was running out on the tempestuous relationship; the fundamental difficulties which led to the 1965 parting could not be resolved.  In November 1971 Vulcan cancelled Conmaco as a Vulcan distributor because, as Vulcan’s President H.G. Warrington noted, “the general business objectives of Vulcan and Conmaco are basically inimical.”

In spite of the apparent finality of that cancellation, things weren’t quite over just yet.  In August 1974 George Daniels of Conmaco’s Chicago branch had facilitated the test of Vulcan’s Decelflo muffler.  Vulcan reinstated Conmaco’s Chicago branch only as a Vulcan dealer in October of that year, but it was short lived: within a year Vulcan once again cancelled the agreement, which proved to be the final one between the two organisations.

Conmaco went on to produce a line of Vulcan style air/steam hammers to cover most of the size range of the ones Vulcan had manufactured.  During the 1970’s and 1980’s Conmaco was a competitor to Vulcan both onshore and offshore.  Things flared up again in 1978 when Vulcan accused Conmaco of infringing upon its Vari-Cycle stroke control patent with Conmaco’s energy selector device.  Conmaco responded with a cross-licensing proposal, but Vulcan, true to form, flatly refused its request.

Although Conmaco’s product line was developed as a competitor to Vulcan, the fact that the hammers that resulted were basically Vulcan style hammers are a testament to basic durability of both the design and the hammers.  Additionally companies which service Vulcan hammers can also do the same for their Conmaco counterparts.

Additional information:

• Conmaco Operation and Service Manual for Hammer Sizes 50, 65, 80, 100 and 115.

Although Vulcan’s relationship with the Machinists’ trade union at its Chattanooga facility was generally reasonable as such things go, every now and then conflict would arise outside of the triennial (usually) contract negotiations. Probably the most significant of these conflicts–and certainly the best publicised–was the “Turkey Grievance” in 1981. It’s a good way to illustrate the whole grievance and arbitration process, and in itself is an interesting piece of labour law.

The best place to begin this narrative is with the following notice, which was posted in the shop on 16 November 1981:

ALL PRODUCTION AND MAINTENANCE EMPLOYEES

Years ago during a financially successful period, the Company, wishing to share such success with employees, decided to give employees a turkey at Thanksgiving and a ham at Christmas. The Company has continued this practice each year since that time.

Unfortunately, this year has not been a particularly successful year. As a consequence, we regret to inform you that this year we will not provide a turkey at Thanksgiving. We will, however, give employees a ham at Christmas.

The usual procedure in the event an employee had a complaint against Management was to hold a meeting consisting of representative of the Union’s shop committee and Management. If the matter could not be satisfactorily resolved there, the Union would file a grievance. (Sometimes the order between meeting an grievance would be reversed.)

In this case the sequence was a little different. The events were outlined by the Company’s labour attorney, Bernard J. Echlin of Vedder, Price, Kaufman and Kammholz, in a letter to Mr. Douglas D. Walldorff, Acting Regional Director of the National Labour Relations Board in Atlanta:

Before making any decision with respect to the Thanksgiving turkeys, the Company on November 16, 1982 called a meeting of the shop committee of the Union. At that meeting the Company discussed with the committee its proposed course of action. While the committee did not agree with the Company on the matter, neither did it disagree. Nor did the Committee propose any alternate course of action. Following the meeting the Company posted a notice for the information of all employees. A copy of the notice is enclosed. This notice was shown to the shop committee before it was posted. The shop committee did not object to its posting or ask that the Company delay the posting of the notice.

A day or two later a member of the shop committee asked a representative of the Company whether the Company would be willing to meet with Union Business Representative Edward Pierce to discuss the Thanksgiving turkey matter. The Company readily agreed to meet with Pierce and did meet with him. In that meeting Pierce objected to the Company’s proposed course of action but did not persuade the Company to provide employees turkeys at Thanksgiving.

The Union filed the formal grievance (shown at right) four days later. It is noteworthy that Edward Pierce, Directing Business Representative for the Success Lodge 56 of the International Association of Machinists and Aerospace Workers, signed the grievance. Generally speaking a grievance would be signed by a member of the Union’s shop committee or the grievant.

The Company formally responded to the grievance on 1 December 1981 as follows:

This is in response to the grievance dated November 20, 1981 in which the Union alleges a violation of Article 1.1 and other provisions of the agreement between the Company and Union because the Company this year has not provided employees a turkey for Thanksgiving.

Section 15.1 provides that the parties’ written agreement “constitutes the entire agreement between the parties.” Thus, if there were a commitment on the part of the Company to provide employees with a turkey every Thanksgiving such commitment would have to be found in the written agreement. Neither Article 1.1 nor any other provisions of the agreement contain such a commitment.

The grievance describes the Company’s action in not providing a turkey as “unilateral action” and as having taken place “without negotiations with the Union.” Under the express provisions of Section 15.1, the Company had no duty to bargain with the Union with respect to the matter. Nonetheless, despite the provisions of Section 15.1 and long before the Thanksgiving holiday, the Company discussed its intentions with the Union Committee. Thereafter, still long before Thanksgiving, the matter was discussed at the Union Committee’s request with Union Business Agent Edward Pierce. Thus, even if there were an obligation to bargain with the Union with respect to the matter, the Company satisfied such obligation.

The grievance is without merit and is hereby denied.

The articles cited by both sides refer to the Union contract in force, the result of collective bargaining in 1980.

The Union responded by filing an unfair labour practice complaint with the National Labour Relations Board’s office in Atlanta. The NRLB responded on 22 March 1982, in part as follows:

In accordance with the National Labour Relations Board’s decision in Collyer Insulated Wire, 192 NLRB 837 (1971), and pursuant to “arbitration deferral policy under Collyer – revised guidelines, publicly issued by the General Counsel on May 10, 1972, I am declining to issue a complaint on the instant Charge based on my determination that further proceedings on the Charge should be administratively deferred for arbitration.

My reasons for deferring the charge are as follows: the issue raised by the instant charge is one that can be considered and resolved under the grievance arbitration provisions in the current labour agreement between the parties, and a grievance has, in fact, been filed. Moreover, the Charged Party has notified this office, that it is now, and for a reasonable period will be, willing to arbitrate the dispute underlying the charge in the above-captioned case, notwithstanding any contractual time limitations on the processing of grievances to arbitration.

The arbitration process was facilitated by the Federal Medication and Conciliation Service in Washington, DC. Here, the FMCS would submit a panel of names of potential arbitrators to both parties. Those submitted had met the Service’s requirements to act as an arbitrator. If one of these was suitable to both parties, the arbitration would proceed. If none of the names submitted were mutually satisfactory, the Service would submit another panel and the process would be repeated.

The FMCS submitted its first panel on 8 December 1981; none of the members of the panel were acceptable to both sides. Since the NRLB had elected to defer the unfair labour practice charge until arbitration was resolved, the Union initiated a request for another panel of arbitrators, which the Company co-signed and sent back to the FMCS (see right.) The FMCS submitted a panel of five to both parties on 6 March 1982. Mr. Ralph Roger Williams of Tuscaloosa, AL, proved acceptable to both parties and was selected to arbitrate this case.

Mr. Williams submitted times that he could be in Chattanooga for the arbitration meeting, and the meeting was set for 1000 8 June 1982.

At the arbitration meeting both sides presented their case, calling witnesses and cross-examining opposing witnesses. After the meeting both sides presented post-hearing briefs on the subject, which could comment on the testimony given (both positive and adversely) and present what each side felt was the applicable law in the case.

The arbitrator issued his ruling in favour of the Company on 30 July 1982. His decision can be read here. The decision came as a shock to the Union (and frankly I was surprised as well.)

Without a favourable decision from the arbitrator, the Union opted to let the unfair labour charge lapse. It lapsed so thoroughly that, on 30 January 1984 (nearly a year and a half after the arbitration ruling) the NRLB contacted Union and Company alike to see how things were moving along. The Company responded by submitting a copy of the arbitration to the NRLB. Although the Board offered the Union the option for appeal, the Union did not opt to do so, and the matter of the Thanksgiving turkeys came to a close.

The case was significant enough that the following notice appeared in the 25 October 1982 edition of U.S. News and World Report:

Turkeys given to union employees are a gratuity that can be withdrawn at any time, holds an arbitrator. Vulcan Iron Works halted its custom of giving turkeys to machinists after a poor financial year. The arbitrator finds against the union after determining that its contract did not mention the gifts and that employees had not considered them income, since they failed to declare them for tax purposes.

Although the Company regarded the matter as a significant victory, its long-term effects were decidedly mixed. With the collapse of the offshore oil industry, Vulcan’s business suffered in the years immediately following the grievance. The Union opted to pass on contract negotiations in 1983 and 1984, making a three-year contract into a five-year one. It also opted to leave the Machinists’ pension plan in 1992 for a 401(k), a significant step since trade union’s traditionally regard participation in the union’s plan as an important way of bonding the members to the union. On the other hand, decertification–even when an important union “right” was not recognised as was the case here–was never seriously entertained at Vulcan, and the Machinists continued to represent the shop employees until the plant was closed in 1998. (For some of my thoughts as to why people stick with unions even when the economic benefits are not apparent, click here.)

This article first appeared in the First June 1993 issue of Pile Buck, and is reproduced here with some updates. Related information is as follows:

• Click here for trip reports of the one test of this device in North America.
• Detailed technology specifications for the next generation of pile cutters based on this method are available; click here if you are interested in contacting us about this.
• Vulcan’s obtaining the patent rights for this device was a long process; for its hilarious conclusion, click here.

Introduction

When the driving of a concrete pile is complete, the next step is to connect the top of the pile with the structure it is holding up. To do this, it is frequently necessary to have the reinforcing bar protrude above the top of the pile. There are two basic ways to accomplish this:

1. fabricate the pile with protruding reinforcing bar or cable; or
2. to cut off the top of the pile in such a way as to leave the reinforcing bar or cable exposed for connection.

Method (1) would seem to be the most straightforward, but there are many hidden pitfalls. The first is the obvious one, i.e. in the handling of the pile, it is easy to damage the protruding steel. Another is related to driving the pile with exposed steel. For many years, hammer manufacturers cast pedestal driving heads, as shown in Figure 1, that would allow enough space for protrusion. Many manufacturers have abandoned pedestal driving heads because of reliability problems, since the allowance for the reinforcement cage leaves little room for the steel itself. Another solution is to use a three piece cap arrangement, with one cap mating to the hammer, another the pile and a piece of pipe in the middle. The protruding reinforcement steel protrudes into the inside of the pipe. While this has been used successfully, it results in a three piece cap with the attendant weight and additional interfaces for the driving energy to pass through.

Method (2) requires that whatever method is used to cut off the pile allow the reinforcement steel to remain after the top concrete is gone. Although there are methods to accomplish this manually, it would be more productive and consistent to use an automatic device to accomplish the task. This paper describes such a device, its development and its application.

Development

Russia is a place where concrete piles play an important role in foundations therefore, it should not be surprising that the problem of concrete pile cut-off should occupy the attention of Russian researchers and construction organizations. Attempts to mechanize this process were made in the USSR in 1960’s when there were manufactured devices which cut concrete and reinforcement bars by rotating diamond-metal disks (concrete pile saws), as well as devices which crushed pile concrete by effort perpendicular to the pile axis, which exposed reinforcement bars for their further cutting by any method available. There were also developed and produced devices which 1) provided pile cracking at a predetermined level, 2) acted in a “clipper” mode to cut piles, 3) twisted the pile at a predetermined level, and 4) cut the pile by heat, crushing, ultra-sound and other methods.

For a variety of reasons these methods have not found widespread use in Russian construction works and up to now the process of protruding pile parts breaking and removal is not mechanized. It is carried out manually concrete crushing is performed by jackhammers such as are used in coal mines reinforcement bars are then cut by electric or resistance welding, gas or flame cutting.

Through extensive intelligence gathering, Russian organizations kept track of the development of pile cutters (automatic pile cutters) produced outside of the country. Amongst them there are devices produced by “Sanva Kizai” (Japan), “Diaber” and “Pilecut” (Switzerland), “HPSI” (USA), “Taets” (Holland), etc.. During analysis of these devices it was found out that all of them are based on the principle of pile concrete crushing by effort applied in transverse direction perpendicular to the pile axis. As a result of this effort the reinforcement bars were exposed and then cut by different ways at a predetermined level. It is necessary to note that all the operations concerning cutting of reinforcement bars are carried out manually in all of these machines.

In cooperation with the Far East Institute of Construction, NPO “VNIIstroidormash” developed a new type of concrete pile cutter. These organizations carried out both scientific research and experimental tests using special test racks a prototype model being tested is shown in Figure 2. The researchers discovered that, with transverse compression of the pile at two levels and an application of a longitudinal breaking force, pile breakage will take place without deformation of the reinforcing bars (the concrete then moves relative to the reinforcing bars.) The researchers also discovered the basic parameters of the machine, such as the sizes of the compressing plates and the value of the compressing force which provides tight and reliable compression of the pile while preventing uncontrolled pile breaking. This discovery, coupled with discoveries in the nature of pile cracking, enabled these organizations to develop the new type of pile cutter, which basically combined the bond separation and the pile cracking in the same area of the pile, the cracking taking place both in the same plane as the bond failure and also above and below it. The index number of this machine is SP-88 (SO-270.) It has been manufactured both by VNIIstroidormash’s own pilot factory and a production factory. Such as unit is shown in Figure 3. This pile cutting machine was patented in the United States (U.S. Patent number 4,979,489).

 

Construction and Operation

The principle behind the new pile cutter is shown in Figure 4. According to this method, the pile (1) is compressed by two hydraulic grips (2) and (3) located at two levels near each other which provide uniform pile compression at all four side planes (Figure 4a). Then, vertical force parallel to the pile longitudinal axis is applied for purposes of completing the cutting process (Figure 4b). The location of pile concrete breaking level is determined by tension concentrators (4) which are installed at the hydraulic grips. The basic design of the pile cutter provides simultaneous breaking of both the reinforcing bars and the concrete, but the design may also provide for the protrusion of the reinforcement bars for their further embedment into a cast-in-place pile cap. Having broken the pile, the machine can also carry the cut-off pile section away for proper disposal.

A more detailed view of this device is shown in Figure 5. It consists of two grips (1) and (2) located one under another which are interconnected by the break cylinders (3), whose axes are parallel to the pile axis. Each grip in its turn consists of clamping sections (1a) and (1b) which are connected with each other by pile compression horizontal cylinders (4) which are attached to these sections by hinges. On the contact side of the pile each clamping section is completed with changeable plates (5). These plates have corrugated surfaces to provide tight contact with the pile and prevent sliding during pile breaking. Moreover, triangular teeth are welded into the lower parts of the upper grip changeable plates. These teeth act as tension concentrators which during pile compression dig into the pile and provide concrete cracking at the plane of breaking.

The pile cutter is completed with four (4) vertical struts located at the upper grip which are intended for suspending the pile cutter off of the crane for handing of both the pile cutter and the pile parts which are removed during operation. Typical suspension of this device is shown in Figure 3. The design of the grips consists of hinged and interconnected sections. Special rod synchronizers guarantee pile compression of square concrete pile, whether the pile is actually square or not (frequently the pile is in reality a parallelogram or trapezoid).

The pile cutter is used in combination with a hoist device of at least three metric tons load capacity to handle both the pile cutter and pile cut offs. If the hoist device is hydraulically operated the pile cutter can be driven from the hydraulic system of the crane and controlled from the operator cabin if the load hoist device is not hydraulically operated the pile cutter is driven from a special separate power pack which may be included with the pile cutter. This power pack may be driven from an electric motor or an internal combustion engine.

The pile cutter hydraulic system is completed with three (3) flow dividers to provide synchronized motion of the four vertical break cylinders during their extension, thus providing parallel movement of upper grip relative to the lower one. The pile cutter is connected with the hydraulic pump by two hoses and is controlled by one three position spool valve which is closed in neutral position and reverses the hydraulic flow in extreme positions. At one extreme position operations of pile compression and breaking are carried out at the other the clamps open, first the lower and then the upper. This takes place because of two safety valves applied in the pile cutter hydraulic system. One of these opens fluid flow into the break hydraulic cylinders when the pressure in the compression cylinders has reached a sufficient level, and thus guarantees the pile is gripped properly before pile cracking begins. The other safety valve provides opening of upper grip only after the lower grip opens and touches the upper grip.

Modes of Operation

The pile cutter can operate according to three schemes, as shown in Figure 6. Scheme 1 (Figure 6a) makes the concrete break no higher than 50mm (2″) off of the ground the reinforcement bars are exposed when the crane pulls up on the cut off section. In this case the pile cutter is lowered onto the pile with the upper and lower grips being fully opened, and is set on the lower level in height. When hydraulic fluid is supplied to the machine the, rod ends of the horizontal compression cylinders of the upper and lower grips are pressurized first. When the pressure in the hydraulic system reaches 140 bar (2000 psi) the pressure actuated hydraulic valve operates and the rods of the vertical cylinders begin to extend. This forces both the concrete and the reinforcement bars to break, but also another break is induced by the teeth concentrators at ground level. When the separation is complete, the pile cutter is hoisted by the crane winch with its upper and lower grips closed and is moved to the place where the pile cut offs are to be disposed. The lower part of the concrete is pulled away like a stocking since it was separated from the pile by the teeth welded on the plates of the lower grip. The additional force on crane hook to expose the reinforcement bars by pulling away the concrete does not exceed 1.5-2.0 metric tons. When the direction of hydraulic fluid flow is reversed, first the lower grip opens and the vertical break cylinder rods are retracted then, the upper grip opens and the broken off parts of the pile is free for disposal.

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To operate according to Scheme 2 (Figure 6b), the pile cutter operates the same way as in Scheme 1, but the concrete is removed and the reinforcement bars are exposed by the repeating of pile breaking operations. The first break cuts both concrete and reinforcement bar the pile cutter is then lowered and the second break is induced in the concrete only, and the cut-offs are pulled away as they are in Scheme 1. If the reinforcement bars are less than 400mm (15 3/4″) high off of the ground, there is no need to break any reinforcement bars at all but to simply pull the concrete away from them.

Scheme 3 (Figure 6c) involves breaking the reinforcement bars without first exposing them. In this case operations on pile installation, compression and breaking are first performed. Then, the pile cutter with its upper grip closed and lower grip open is removed from the pile left in the ground and is transferred to the disposal place for the pile cut-offs. When the upper grip is open the pile cut-off is disposed of.

Conclusion

Depending upon the scheme used, the end result of the pile cutter’s work is to leave pile tops all leveled off to a specified design elevation with crack less flat tops and with either protruding reinforcement bars 200-350 mm (8″-14″) long, fully prepared for embedment into a cast-in-place pile cap (Schemes 1 & 2, Figure (6a) or (6b)), or without protruding reinforcement bars for installation of a precast pile cap (Scheme 3, Figure (6c)).

In accomplishing its task, this pile cutter has the following advantages:

1. Higher productivity compared with other machines.
2. The possibility of exposing the reinforcement bars for further embedding into a cast-in place pile cap
3. Improved safety for transferring of pile cut-offs for proper disposal.

Although Vulcan never placed it into production, the Single-Compound hammer was one of Vulcan’s more interesting experimental hammers, and under different market circumstances has the potential of success.

Although a general long-term success, Vulcan always recognised that the product life of the air/steam hammer line wasn’t infinite, especially offshore. Given the difficulties of developing an underwater hammer, Vulcan decided it needed a hammer that:

• Was, if anything, simpler than the hammer it had been producing;
• Was less subject to endless rebuilding; and
• Had lower steam or air (energy) consumption, which was an issue relative to both diesel hammers and the Menck hammers, which used the steam expansively.

The last point was best achieved if Vulcan hammers themselves used the steam or air expansively. Vulcan was no stranger to this; the California series of hammers did so for nearly three decades, albeit with a valve system that was tricky to manufacture. MKT added complexity to this scenario with their “C” series hammers. These in turn were the basis of the “Airmizer” hammers which Vulcan built under licence from Horn Construction in New York.

The solution to this came from the linear vibrator, which had a piston type ram with slots admitting air at the end of the stroke and the air expanding upon closure of the slots to push the ram towards the other end. It was a simple step to make this process “one-ended” and produce a hammer which operated in the same way, only in this case throwing the ram upwards and allowing it to fall downward and impact the pile, compressing the air after it passed the exhaust ports.

The concept for this was first developed in late 1981, and plans began after that to build a prototype. The prototype had a 300 pound ram, and was built entirely at the Special Products Division in West Palm Beach. The prototype was tested successfully in the Spring of 1983.

With the success of the small prototype, the field prototype, the SC-3 (with a 3000 kg ram, photo at beginning of article) was built. It was tested twice on projects in West Tennessee in the summer of 1983. The tests were successful, although they indicated that the ports on the hammer needed lowering to increase the impact velocity of the ram. (Diesel hammers also slow their rams down considerably by the compression of the air before impact and combustion, which has led to the derating of these hammers’ rated striking energy.)

Although the hammer worked well, Vulcan did not pursue it for two reasons:

• The offshore market collapsed with the oil prices, which removed on of its potential markets.
• The rise of dynamic testing on shore led many state DOT’s to require a stroke control feature on hammers to prevent tension cracking during easy driving of concrete piles. The SC hammers did not have this.

Vulcan Foundation Equipment revived and developed the SC concept. Below is the SC-15/4, with a 3.75 kip ram and a 4 ft. stroke, driving wood piles in New Orleans for Boh Brothers, in May 2013.

Another test took place the following year in Kenner, LA, as shown in the clip below.  The results of that test became a centrepiece of the project Improved Methods for Forward and Inverse Solution of the Wave Equation for Piles.