The third in our series of vulcanhammer.net ads for Pile Buck include this one, showing a Nilens diesel hammer driving sheet piling using a “spud” or “rail” type leader in the back. Nilens was one of Vulcan’s more interesting adventures in pile driving equipment. The method used is a typically European practice that has found […]
At one point or another in its history, Vulcan attempted to produce or market every type of pile driver made. Probably the persistently least successful type were the diesel hammers. Vulcan’s failure to manufacture and/or market a widely accepted diesel hammer was a significant long-term problem for the company.
Nevertheless diesel hammers are an important and interesting type of impact pile driver. This section of vulcanhammer.info discusses diesel hammers in general and Vulcan’s several attempts to enter the market.
- Beginnings of Diesel Hammers in the U.S., and Vulcan’s First Response: the IC-65
- Nilens–Vulcan’s Belgian import, and in many ways the most successful of Vulcan’s diesel offerings
- Liquid Propane Gas (LPG) hammer–an adaptation of the Nilens hammer to address the issue of pollution
- The IC-30/30D/33D Hammers: Vulcan’s own diesel that made it to market–sort of
- The “V” series diesel, Vulcan’s adaptation of Russian diesel hammers and its last attempt at a diesel hammer
- Russian Diesel Hammers: the hammers that came before the “V” series
- Competitors: just about everyone has them. Here are the field service manuals for two which Vulcan encountered for its diesel hammer:
- Kobe Diesel Hammer Field Service Manual: for their K13, K22, K32 and K42 hammers. The Kobe hammers were the first diesel hammers marketed in the U.S. on a “sell them cheap and sell a lot” philosophy, and this was especially true in the South, where they were very prominent for many years. This idea has been repeated with the “Chimag” hammers which are virtually ubiquitous in the U.S. today.
- IHI IDH-J22 Field Service Manual. IHI was Menck’s representative in the Far East, and in China Vulcan met and bested them. IHI also developed an interesting diesel hammer where the fuel pump actuator was powered by the compressed gases in the combustion chamber. Unfortunately the mechanism tended to jam when dirty, which was about all the time with a diesel hammer.
Vulcan’s last foray into diesel hammers was, in many ways, one of the most interesting ventures in the company’s history. It was certainly one of the most involved.
In 1987 Vulcan first met with Russian (then Soviet) trade representatives in Washington concerning marketing Vulcan’s offshore hammer line in the Soviet Union. It’s interesting to note that the Soviet trade office was just around the corner from the hotel where Ronald Reagan was shot in 1981. The Soviet Union had enormous oil and gas reserves and, not to be outdone by the Chinese, were beginning to solicit foreign assistance in exploiting these resources. (Even having lost the other republics in the break-up of the Soviet Union, Russia remains rich in hydrocarbon reserves and a major producer.)
The Soviets had other ideas. Never much on spending their hard currency on lining American corporations’ pockets (they weren’t well endowed with hard currency to start with,) they invited Vulcan’s people to Moscow with another objective: to convince Vulcan to market Soviet pile driving products.
Vulcan’s personnel made the trip in April 1988, and were regaled with several interesting types of equipment, including the vibratory hammers (native to the country) and the concrete pile cutter. But the most significant products were the Russian diesel hammers, which they demonstrated to Vulcan’s personnel at the Central Testing Facility (TsNIIP) in Ivanteevka, northeast of Moscow. (In addition to scientific testing, this facility also supplemented this activity by raising pigs.) These were the water cooled variety, produced at their plant in Sterlitamak, near the Urals. (More information about these can be found here. Vulcan personnel also went beyond Ivanteevka to Zagorsk to visit Russian Orthodox Church personnel.)
Although the hammer was simple and ruggedly built (something Vulcan liked to see in a product) the water cooling was a problem. American contractors never took to water cooling diesel hammers, even though it was certainly, in theory at least, the best way to do so. It was an obstacle the Japanese such as Kobe and Mitsubishi had to overcome when they marketed their hammers in the US in the 1970’s, and they largely did so with very competitive pricing. Neither Vulcan nor the Soviets, the latter working through their trade organisation, were prepared to really get the details of such an arrangement, and so Vulcan returned to the US empty handed. (Vulcan did get a chance to propose their offshore hammers, but this too came to nothing.)
At this point all seemed at a dead end, but by 1991 the Soviet Union was unraveling and Vulcan had established meaningful contact with some of the people it has met three years earlier. Given the economic conditions in Russia and Vulcan’s own priorities, the emphasis had shifted to Vulcan acquiring Russian equipment and technology, and the diesel hammers were high on the list.
The following year Vulcan personnel visited Russia again with the idea of acquiring the Sterlitamak hammer. Sterlitamak was the only Russian organisation which actively exported diesel hammers, and the pricing they had proposed (facilitated by the slide of the ruble) would give Vulcan what it was looking for: a proven diesel hammer, economically priced, which would allow it to repeat L.B. Foster’s blitz with the Kobe hammers twenty years earlier. (This kind of blitz was actually carried out by some of Vulcan’s competitors with the Chinese made hammers later in the decade and into the new millennium.)
Sterlitamak, however, got cold feet at the idea of selling their product at the price they originally proposed, so Vulcan was forced to look elsewhere for equipment. In doing so they discovered that not only did other manufacturers exist, but that they produced air cooled hammers, which is what Vulcan was looking for to start with. The first plant Vulcan visited was in Lyubertsy, south-east of Moscow, shown in the video below.
Vulcan purchased a few of their 2500 kg ram hammers. Below: the “before” (left, September 1993) and “after” (right) of the Lyubertsy manufactured diesel hammers. The biggest challenge (as with Nilens) was to move the fuel tanks (one on each side of the hammer, like the old XJ6 Jaguars) up and flatten them to get the hammer into 26″ leaders. Vulcan rechristened it the V25 Series 1 hammer.
Vulcan also acquired 1800 kg ram hammers from a plant in Podolsk, south-west of Moscow.
Almost two years later Vulcan visited a military plant in Bryansk, which produced equipment for its railroad troops, as shown below.
From this plant Vulcan purchased some 1250 kg ram hammers.
What Vulcan ended up with were hammers which were economical enough, but weren’t intended for export. (They suffered from a common Soviet problem: well executed design, but not so good execution in manufacturing. The Bryansk hammers, being from a military plant, were the best.) Vulcan was required to make modifications to the Podolsk and Bryansk hammers as they did with the Lyubertsy ones.
At this point things went awry on Vulcan’s end. Vulcan certainly did manage to deal with the technical and quality issues in front of it. But it could not come to an internal consensus on how to market them; the Kobe model wasn’t universally accepted. In the midst of this Vulcan’s other problems took precedence and the Series I program fell by the wayside.
Vulcan never intended the Series I hammers to be the last word on this. It commissioned the design of an air cooled “Series II” of hammers which ranged in size from 1250 kg ram to 7500 kg ram. Vulcan’s idea was that they would have a hammer which could be built in Russia, the US or wherever manufacturing was the best. The series design was completed but none were ever built, and so Vulcan never got the chance to overcome its past history and bring a viable and economical diesel hammer to market.
With Nilens gone and the LPG hammer unsuccessful, in 1978 Vulcan found itself without any kind of internal combustion hammer. It passed up the opportunity to purchase the Link-Belt diesel hammer line and attempted to develop its own. The effort that resulted was the IC-30/30D/33D hammer line.
Vulcan’s starting point was the Nilens N-33 hammer, which was equivalent to a Delmag D-12. In the course of development, however, Vulcan attempted to make “improvements” on the Nilens designs. Most of these, unfortunately–the use of a single-piece casting for both cylinders, ram and anvil and others–represented an attempt to adapt the diesel hammer to Vulcan’s customary manufacturing methods. It was mostly these which proved the downfall of the line.
The first hammer, the IC-30, was completed in 1980. After some testing the hammer was released for the market, and the name was soon changed to the 30D or 33D to get away from the “IC” (too much like “ICE” or International Construction Equipment for Vulcan dealers’ tastes.) It achieved some successes, but its weaknesses made it expensive for Vulcan to keep it in the field. Compounding the technical problems was the strong U.S. dollar at the time, which made the German made Delmag relatively cheap.
All of these contributed to the eventual decision to recall the hammer. By the mid-1980’s Vulcan was once again out of the diesel market. By that time the vibratory hammers were achieving success and Vulcan’s product line was broadened in another way.
The one spin-off that survived the hammer–and indeed Vulcan Iron Works itself–was the universal/filler cap system. This is currently supported by Vulcan Foundation Equipment. Information (and the field service manual) for this hammer is found in the Vulcanhammer.info Guide to Pile Driving Equipment.
As the Nilens concern inched (or more accurately millimetred) its way to receivership, Vulcan embarked upon a project using one of their hammers that, had it succeeded, would have made an interesting addition to Vulcan’s lineup: the Liquid Propane Gas (LPG) hammer.
As was the case with noise pollution, the 1970’s were also the years when the U.S.’s commitment to clean up (well, in one sense) its air kicked into high gear. Diesel technology, although fuel efficient, tends to produce a great deal of particulate matter. This is true both with diesel engines and with the diesel hammers. With the latter, emission control is even more problematic than with diesel engines. As the combustion configuration (compression ratio, fuel mixture, position of the combustion chamber itself) varies with the hammer’s varying interaction with the pile, controlling the particulate matter is more difficult than with diesel engines.
Vulcan’s concept was to power internal combustion hammers using a fuel with no particulate matter at all, in this case liquid propane gas (LPG.) To do this they enlisted the help of John Kupka, who had earlier in the decade designed the linear vibrator and before that the Airmizer compound hammer. In 1974 plans were drawn up for an LPG hammer, and a Nilens diesel hammer was modified for the testing.
In spite of several design changes and the inclusion of another designer to the task (John Lerch, who later oversaw the designs of the 5150 and 6300 hammers,) the LPG hammer never got out of its prototype stage, and the project was ended in 1976.
Diesel hammers have had their environmental problems, and are banned in certain places. But they have also had their successes, with new and improved fuels to reduce particulate matter, biodiesels and environmentally friendly lubricants. But now we have the drive to reduce carbon emissions.
The end of internal combustion hammers? Or fuel cell hammer, anyone?
One of Vulcan’s more interesting–if not necessarily most profitable–business partnerships was with the Nilens concern in Belgium. This page outlines the company and its product line.
Note: We have extensive technical information available on the Nilens product line, especially the diesel hammers. Click here if you would like to contact us about this.
When Vulcan began to deal with Charles Nilens S.P.R.L., they were located in Vilvorde (Vilvoorde) at 52, Avenue de la Station. Vilvorde is north of Bruxelles (Brussels); it is the same city where William Tyndale, the first person to translate the Bible directly from the Greek and Hebrew into English, was executed for his activities in 1536. In the late 1960’s Nilens secured new offices at 7-14 Houtemstraat in Peuthy (Peutie), also in Vilvorde, and were then known as Materiel Nilens (MANIL) S.A.
Vulcan’s first agreement with Nilens came in June 1963, where Nilens agreed to be Vulcan’s distributor in the then European Common Market’s six countries: the Netherlands, Belgium, Luxembourg, France, and West Germany. In September of the same year the two companies signed an arrangement whereby Nilens would manufacture under license the Vulcan product line. At the time Nilens’ managing director was Jean Willy Nilens. Vulcan also distributed portions of Nilens’ product line in the U.S., as will be described below.
The early years of the relationship were exciting, with numerous trips to Europe by Vulcan executives (complete with silly questions by travel agents) and with a visit by a Belgian prince to Palm Beach.
Nilens for its part made a few Vulcan hammers under license, but the predominance of diesel hammers in Europe made the appeal of air/steam hammers limited.
The Product Line
Nilens’ product line broke down into four parts:
- Single-acting diesel hammers, from Vulcan’s standpoint, the most important part of Nilens’ product line. Nilens produced three single acting diesel hammers:
- N33, with a ram mass of 1250 kg and a rated energy of 3125 kg-m
- N46, with a ram mass of 1800 kg and a rated energy of 4500 kg-m
- N60, with a ram mass of 2400 kg and a rated energy of 6000 kg-m
- “T” series double-acting air/steam hammers (left), similar to the MKT “B” series machines (9B3, 10B3, 11B3). These were primarily intended for installing sheet piling.
- Impact pile extractors, held together using a cable wrap system (right). They were a superior extraction machine to Vulcan’s extractors, albeit more complex and expensive.
- Pile driving rigs, with leader mast and carriage. This is more typical of European manufacturers (Junttan is a good modern example of this.)
Three of these are described below.
Nilens Diesel Hammers
Operation of Nilens Single-Acting Diesel Hammers
|The piston, which in fact is the ram, is raised by the trip mechanism, which is attached to the hoist line. Air enters the cylinder as the piston uncovers the exhaust ports. When the trip mechanism makes contact with the cam, the piston is released automatically. The trip mechanism continues up until it is arrested and held by a spring loaded dog.
Diesel hammers are generally either of a cast construction (like the current Delmag hammers and their progeny) or fabricated (as with the Russian diesels or MKT.) Nilens (along with the older Delmags) was something of a hybrid; an iron ram rode in tubular steel cylinders, with a cast “sleeve” complete with cooling fins fabricated into the hammer around the combustion chamber. When Vulcan designed its own diesel hammers, it went to a cast lower cylinder, with uninspiring results.
|The piston falls due to gravity and depresses the cam, which actuates the fuel pump. The fuel pump injects a measured amount of fuel oil into the concave top of the anvil.
The Nilens’ fuel pump was unique in that it used an internal cam/plunger instead of the external type common on Delmag and other fuel splash delivery systems. It was not a positive displacement pump either; it was a pressure compensated one, with fuel entering (and excess fuel returning) through a needle valve in the top of the pump. When manufactured properly, the pump worked well, but manufacturing and design variations were the chief weaknesses of an otherwise good diesel hammer.
|The piston blocks the exhaust ports as it continues to fall. The cylinder is now a closed chamber, between the piston and anvil, and compression builds up. The convex end of the piston strikes the fuel oil in the top of the anvil and sprays it up into the hot compressed air in the compression chamber, which causes it to ignite. The resulting explosion drives the piston up and adds to the energy already delivered to the anvil by the impact of the piston. The piston uncovers the exhaust ports on the upstroke, permitting the exhaust gases to escape and fresh air to enter the cylinder for the next cycle. To lubricate the piston and cylinder wall, oil is automatically ejected from the reservoir in the top of the piston. The anvil is lubricated by four grease fittings.|
Nilens “T” Series Double Acting Hammers
Nilens Pile Extractors
Vulcan was able to sell and rent a number of Nilens diesel hammers in the U.S.; some of them were operational for many years. They ended up outlasting the company itself. In 1976 Willy Nilens fled to Spain; the company went into receivership, the product line was acquired by Intermat, and the Nilens concern passed into history.
Until World War II driven piles in the U.S. were installed by one of two means: drop hammers or steam hammers. By that time some of Vulcan’s competitors (Union, Industrial Brownhoist) were falling by the wayside, and the steam hammer market was becoming a two-sided match between Vulcan and MKT, with the Raymond hammers still produced by and for one organisation.
Development of Diesel Hammers
In Germany, however, the diesel hammer had been developed by Delmag in the 1920’s. The operating cycle of the diesel hammer is described in the article on Russian diesel hammers. Also explained in this article are the two types of diesel hammers: rod and tubular type. Delmag developed both types, but the tubular style became and still is the overwhelmingly predominant style of diesel hammer. All of Delmag’s hammers were single-acting, i.e., all of the kinetic energy of the hammer being produced by the ram falling through gravity without assist. The fuel system was a departure from engines in that it used the “splash” system, which placed the fuel in the combustion chamber without atomisation.
Although the diesel hammers have many conceptual and theoretical complexities (a fact that Vulcan found out the hard way,) the result is a relatively light and simple hammer, burning diesel fuel directly in the machine without the need for an external boiler or air compressor (or the personnel to operate them.) This result, although distasteful to steam hammer manufacturers and trade unions alike, was popular with contractors. The Delmag hammers made significant inroads into the pile driver market in Europe and eventually spawned imitators on the Continent such as Nilens, Hera and the like.
The technology made its way to the U.S. by way of World War II, when a captured Delmag hammer was brought from Germany. The Syntron concern was the first to actually manufacture a commercially viable diesel hammer. They made two major changes to the Delmag concept: a) they added engine-style atomised fuel injection and b) they included a dashpot type bounce chamber in the top to increase the blow rate. The result was a hammer which was a diesel hammer but had the blow rate comparable to air/steam hammers, which resulted in faster pile installation.
The Syntron hammer was acquired by Link-Belt, which manufactured it until the late 1970’s, after which the product line was acquired and subsequently expanded by International Construction Equipment.
The success of this hammer led to MKT developing a diesel hammer, and Delmag exporting its hammers to North America. The growth in popularity of these hammers forced Vulcan to make some kind of response, and that response came in the late 1950’s in the form of the IC-65.
The IC-65 had the same ram weight and similar energy to the Vulcan 06 and 65C hammers (and the Raymond 1-S hammer.) The basic concept was to embody an internal combustion hammer into a Vulcan-style frame. The hammer had many innovations, including true double action (combustion chambers firing both up and down,) independent starting mechanism (the Delmags used the European leader rails for the crab/starting device,) supercharged and forced-scavenged cylinders, and many other features.
The idea of the hammer was not only to make a diesel hammer “look like a Vulcan,” but also to address difficulties of diesel hammers then and now, especially the difficulty in starting with low pile resistance.
The hammer was largely the concept of Campbell V. “Doc” Adams, Vulcan’s chief engineer and a designer for Vulcan for most of the twentieth century. Details on the hammer can be found in the U.S. patent that was awarded to him for the hammer.
Unfortunately (and Vulcan repeated this pattern with the 30D series of hammers) there were a few too many innovations in the design without the ability to test the concept before a prototype was built. Testing, modification, more testing and more modification lumbered on in the late 1950’s and early 1960’s, spanning Vulcan’s move to Chattanooga. But in the end the IC-65’s development was suspended, and Vulcan turned to Europe for its diesel hammer needs.
L.V. Erofeev, VNIIstroidormash
V.A. Nifontov, VNIIstroidormash
D.C. Warrington, Vulcan Iron Works Inc.
- This article first appeared in the First May Issue 1993 of Pile Buck. It is reproduced here with a few changes. .
- Additional information (including some detailed theory on diesel hammer operation) can be found in the article Tubular Diesel Hammers, which was written by one of the authors of this article.
- The complete history of Vulcan’s dealings with the Russians concerning the diesel hammers, including their importation of diesel hammers from various Russian sources and the commissioning of a new series of diesel hammer designs, can be found here.
Pile foundations have been around for quite a long time, and to many people justification seems superfluous. Nevertheless, given the speed of technology advance and the technical amnesia this can create, it is worthwhile to stop and remind ourselves that pile foundations have both economic value and technical appeal. The whole process is an enormously complex one in all of its aspects, whether we consider the mechanics of the impact or the transfer of the load from the pile into the soil and the soil’s response to it.
In Russia, a country that is admittedly ready made for deep foundations, pile foundations are the most widespread foundations for buildings and structures in civil, military, industrial and hydrotechnical construction because their use instead of ring foundations makes it possible to significantly reduce amounts of earth moving works, to reduce labour consumption by 50%, and concrete consumption by 33-50%. Pile foundations additionally provide building settlement that is both lower and more uniform than ring foundations. This fact is especially important in the construction of block-type and large panel buildings, such as the high rise apartment buildings one normally associates with Russia.
To drive these piles and thus reap the benefits of these advantages, the most widespread machines for driving piles are diesel hammers. Their main advantages are 1) independence from external power sources such as steam boilers, air compressors, generators, or hydraulic power packs, 2) high productivity, 3) simplicity and convenience of operation, and 4)relatively low price of manufacturing. Eighty percent (80%) of all piling works in Russia are carried out by diesel hammers. Each diesel hammer during a year fulfils piling works which cost forty (40) times as much as the price of the diesel hammer itself.
Overview and Development of Russian Diesel Hammers
The principle of operation of all diesel hammers is based on the two stroke internal combustion engine with compression ignition. The impact force of a diesel hammer is the result of both the direct impact of the ram on the anvil and the pressure of air-fuel combustion. Diesel hammers are divided by their design into two types, tubular and rod type. Rod type diesel hammers, as shown in Figure 1, are used for driving light concrete and sheet piles. Tubular diesel hammers are mostly used for driving medium and heavy concrete and steel piles. The high driving capacity of tubular diesel hammers is gained because of their relatively small compression ratio (CR = 15) and high stroke (s = 3000-3300mm) in comparison with rod type diesel hammers (CR = 25-28 s = 2000-2500mm). As tubular diesel hammers are the most widespread diesel hammers both in Russia and elsewhere, this paper is concerned with tubular diesel hammers.
Under normal circumstances, the total annual output of tubular diesel hammers in Russia is about 1,500 units. Diesel hammers for civil needs are produced by three manufacturers. The division “SZSM” is the main manufacturer of diesel hammers in Russia. It produces diesel hammers in five (5) sizes with ram masses as shown in Table 1.
|Impact portion mass,kg||1250||1800||2500||3500||5000|
|Maximum Impact energy,kJ||40||56||82||115||160|
|Frequency of impacts,Hz||0.7 (42 BPM)|
|Size of Square Concrete Piles to be driven, cm||30||30||35||40||40|
|Length of pile to be driven, m||8||12||16||20||24|
|Hammer total mass,kg||2700||3850||5500||7700||10000|
|Working stroke, mm (distance from impact to opening of exhaust ports)||285||310||420||385||680|
|Type of cooling system||water-cooled|
These were originally designed by NPO “VNIIstroidormash” based upon the principle of geometrical similarity; the general layout of these machines is shown in Figure 7. The main feature of these diesel hammers is the presence of the interchangeable cylinder (5) with the water cooling system. The replacement of this cylinder by a new one (which is included in the delivery set) is carried out in case the construction workers manage to wear 1 mm off of the inner walls of the cylinder, a parameter gleaned from sources outside of Russia. In this case there is no necessity to send the hammer to a repair shop. The technical data for these hammers is shown in Table 1.
|1 – upper cylinder
2 – piston
3 – fuel tank
4 – fuel pump
5 – lower cylinder
6 – anvil block
7 – oil hose for anvil block lubrication
8 – water tank
|9 – oil pump
10- oil tank
12- crab guide
13- oil hose for ram rings lubrication
14- filling throat plug
15- drain throat plug
While the original design was basically successful in both production and use, there were a few difficulties. The first concerned the alignment of the cylinders. The interchangeable cylinder contains two flange joints and sometimes during assembly it is very difficult to obtain proper axial precision. Also, the bolts holding the cylinders together would not stay tight and in some cases its life was too short. In response to these problems “VNIIstroidormash” designed the “A” series of hammers, with designations SP-75A, SP-76A, etc.. The technical specification of each of the machines is the same as the earlier design however, in the modified models there is only one flange joint between working and upper cylinder. This feature makes it possible to obtain better axial precision during assembly. The interchangeable cylinder is made of wear resistant material in addition to this, an additional oil pipe line was installed and lubrication oil from the pump was supplied not only to anvil compression rings but to the upper cylinder too. The bolted joints were changed to clamped ones bench tests confirmed the advantage of this type of joint.
The tubular diesel hammer operates as follows (Figure 8): the piston with the assistance of crab (Russian name for the starting device) driven from the winch of the pile driving rig (in common with machines operated in many other places, Russian hammers are operated from a dedicated pile driving rig) is raised to an upper position at which it is released by the crab and falls down under its own weight. Before the bottom of the ram passes the exhaust ports the piston pushes the fuel pump lever and fuel from the pump is supplied to the spherical recess of the anvil. At the bottom of the stroke the piston impacts the anvil. The energy of impact is divided between fuel vaporization and its mixing with heated air and driving of the pile. After a short period of time the air-fuel mixture is ignited and due to the pressure of the expanding exhaust gases the piston is raised up and additional driving impulse is transmitted to the pile.
1 – crab
2 – piston
3 – fuel pump
4 – inlet
5 – cylinder
6 – anvil
|Stages in Cycle:
I – ram up (start), scavenging
II – termination of scavenging, fuel feed
III – termination of compression stroke, blow delivered on anvil block, fuel combustion
IV – termination of fuel combustion, exhaust, beginning of scavenging
Water cooled diesel hammers may operate for a long time at ambient temperatures greater than +40 deg. C without overheating. The heat removal may be increased by a circulation evaporation cooling system use in diesel hammer design. This system consists of separate pipes which are filled with cooling water. These pipes are located on the outside of the lower cylinder connected in lower parts with each other by a circle tank located at the level of the combustion chamber. During operation cooling water is heated very intensively in the tank and begins to circulate inside vertical pipes, providing uniform lower cylinder cooling. Cooling surface in the case of this type of cooling system use is rather large so the operation of diesel hammer at high ambient temperatures is more efficient because of better heat removal. In case of ambient temperatures below freezing water from the cooling system is removed via a screwed plug located at the bottom of the circle tank, and the hammer operates like an air cooled hammer, but with the air circulation through the openings at the upper part of vertical pipes.
Figure 7 shows a general view of the SP-79 diesel hammer, which is typical of the hammers shown in Table 1. The hammer itself comprises a lower (working) cylinder (5), upper cylinder (1, guide pipe), piston (2, impact portion), anvil, fuel pump (4) and crab (11). The lower cylinder is located in the area of maximum internal surface wear and is of short height (not more than 1/3 height of diesel hammer) and very simple design. The processes of compression, mixing, combustion, expansion of exhaust gases and filling with fresh air charge take place in the lower cylinder. The upper cylinder is completed with oil tanks, fuel tanks and pumps, and crab with guide (12). For attachment of hammer lifting cables, two lifting hooks (ears) are welded on the outside of the top of the upper cylinder. At the bottom of the upper cylinder there is the flange for a bolted connection with working cylinder flange. The fuel tank (3) and pump are connected with a flexible hose, which is attached to the outside of the cylinders. To the lower flange of working cylinder the anvil ring is attached by screws to hold the anvil during lowering. At the middle part of the cylinder there are located detachable guides to connect hammer with the leader of the pile driving rig. Piston (2) is located inside the cylinders. Water cooling system comprises water tank (8), located at the level of combustion chamber, with filling (14) and drain (15) ports.
The low pressure plunger type fuel pump is shown in Figure 9, and is intended for fuel supply to the combustion chamber. It is attached to the cylinder with studs and nuts, and it contains a rotatable lever to adjust fuel feed in a continuously variable fashion. A special clamp welded to the cylinder protects the fuel pump from damage. The fuel pump operates as follows: The piston presses plunger (2) via driving lever (1). The fuel pump is thus pressurized the inlet valve of the pump is closed and fuel accumulated in the pump is discharged via ball valve (3) to the combustion chamber. When the plunger moves back to the initial position valve (3) begins to close, valve (4) opens and the fuel pump fills with fuel via the flexible hose from the fuel tank. There exists continuously adjustable fuel feed in the fuel pump. When the adjusting lever (5) is rotated clockwise the amount of fuel to be supplied to the combustion chamber is decreased and when rotated anticlockwise it is increased.
Returning to Figure 7, the lubrication system of tubular diesel hammer consists of oil tank (10), attached to the guide pipe, from which oil with the assistance of oil pump (9) is supplied via flexible hoses (7) and (13) to the lower anvil ring and to guide pipe to lubricate piston compression rings. The oil pump design and principle of operation is similar to the fuel pump, and its general construction is shown in Figure 10.
The crab (see Figure 11) assists the starting of the diesel hammer. It is installed on guide located at the upper cylinder of the hammer. When the crab is lowered along the guides, its linkage engages the piston with hook (1). When the crab is lifted up to the limiting position of the cock and release lever (2) the hook disengages the piston and it falls down under its own weight.
Tubular diesel hammers are completed with pile caps which are installed between anvil and pile, as shown in Figure 12. These caps provide force distribution upon the pile top. The pile cap must provide pile driving into hard soils without pile head damage. A rod is screwed into the lower end of the anvil. The purpose of this rod is to properly center the pile top with the hammer. During driving the rod is squeezed into a wooden washer plate of the pile cap under the weight of the hammer. The anvil is surrounded with 2 pairs of semirings, upper and lower. These semirings prevent contact surfaces from wear and increase the durability of the parts. The upper part of the piston is bored for oil tank with screwed cover. This cover has a screwed hole for small plug to be screwed during operation or ring bolt to be screwed during mounting and dismounting in case of maintenance or repair works.
In addition to the water cooled hammers described here, tubular diesel hammers are produced with air cooling systems. These hammers are similar to the water cooled hammers in their construction except that the water tank is replaced by fins which assist the hammer’s convective cooling. During intensive diesel hammer operation, especially in case of driving heavy piles into hard soils or in case of ambient temperature above +30 deg. C and diesel hammer operation for two (2) shifts a day, the lower cylinder temperature be very high. In this case the stroke is decreased, which decreases the energy per blow.
Diesel hammers were developed to be an economical tool for the installation of pile foundations, and Russian diesel hammers represent a successful fulfilment of that initial purpose. They are designed according to established principles and manufactured to be simple of operate and service. They are viable tools in the real world of foundation construction.