Welcome to vulcanhammer.info, the site about Vulcan Iron Works, which manufactured the durable air/steam line of pile driving equipment for more than a century. Many of its products are still in service today, providing reliable performance all over the world. There’s a lot here, use the search box below if you’re having trouble finding something.
Like its Warrington-Vulcan counterpart, the #1, the 50C was a popular hammer and, along with the 80C, comprised a large block of Vulcan’s production of these hammers. Specifications are below.
Bulletin 70A Specifications
Bulletin 70D Specifications
Bulletin 70F Specifications
Some general arrangements are below. Note that the hammer in the image above sports a bar-type head while these have a sheave-type head; this is explained here.
Some photos are below.
Vulcan 50C hammer, installing sheet piling, Chicago, 1974. Note the yellow Decelflo muffler on top of the hammer; this was one of the first uses of the exhaust muffler.
Vulcan 50C driving piles on a batter using swinging leaders, Hudson, OH. Swinging leaders are usually used to drive plumb piles, but in this case the leaders are stabbed in the ground so that the whole assembly can be leaned back. It’s done but requires considerable skill on the part of the contractor.
Vulcan 50C, driving sheet piling. Vulcan hammers weren’t known to be sheet pile specialists but, as these photos show, they got the job done anyway. As was the case before, an “offshore” type leader was used, where a stub leader was hung from a crane and lowered with the hammer. This is good when the pile is supported at the ground, either by a template or in this case other sheet piles.
A concept for the muffler: mount it directly on the back of the hammer, using a bracket integral to the hammer. A special cylinder head would transmit the air from the exhaust to the muffler. Unfortunately the Decelflo program didn’t get far enough for Vulcan to try this concept.
Vulcan 50C hammer with a two-cable arrangement and 26″ jaws, Chattanooga facility, 16 August 1968. The cable arrangement is similar to the one Vulcan adopted on the offshore hammers. Although it required the use of 26″ jaws, it was surely superior to the “pocket” cables Vulcan adopted about ten years later.
The general arrangements are interesting not just for the 30C but to explain features and variants in the Vulcan product line.
The bar head type 30C shows the way the cushion, driving accessory and top plate mate to the hammer.
The bar type head was easy to connect with the leaders, but did not allow for the mechanical advantage of the sheave. It fell out of favour with the onshore hammers, but came back (with its variant, the suspension head) to be standard with the offshore hammers.
The sheave type head, standard with Vulcan onshore hammers. Frequently, however, contractors will remove the sheave and lift the hammer with the sheave pin, negating the mechanical advantage of the sheave.
The #4, another one of the early Warrington-Vulcan hammers, was the smallest one designed and produced. It was referred to as the “Fish Stake” hammer, because, as Vulcan’s literature explained, it was “used for driving fish stakes for pond nets along the shore and in connection with sheeting cap, for small wooden sheeting.”
Specifications for this hammer are below.
It’s interesting to note that the #4 only had upper rubber bumpers; there were no rubber bumpers on the base. This arrangement was eventually incorporated into the very late Warrington-Vulcan hammers, especially the 5′ stroke hammers like the 506 and 512, in order to strengthen the base.
As was the case before valve liners, the shifting of the cylinder cores necessitated valve settings for each hammer. This was also true of the #4; an example of this for a contractor in Walkerville, Ontario is shown below. Walkerville was built as a “model town” around the Canadian Club whisky distillery. Given the propensity of the owning family for whisky, some return on the investment was appropriate.
“C.V.A.” is Campbell V. Adams, Vulcan’s engineer for many years and the designer of the Super-Vulcan hammers.
Here we link to the operations manual (or “Certificate” as the Russians referred to it.) We trust that you will find this informative as to the operation of this concrete pile cutter, which (to our knowledge) has not been duplicated elsewhere.
The Foster hammers are an interesting part of Vulcan’s last years. The concept was to produce a vibratory hammer under a “private label” arrangement, a novelty for the pile driving equipment industry at the time (although the “Chimag” diesel hammers were a similar concept.) In the early 1990’s Vulcan produced several vibratory hammers for the sheet pile supplier L.B. Foster, merging Foster’s own exciter technology (which was Japanese in origin) with Vulcan’s power pack improvements after parting ways with HPSI.
The purpose of this article, however, is primarily to discuss hydraulic vibratory hammers with an emphasis on the “hydraulic.” Pile driving equipment in general and vibratory pile driving equipment in particular poses challenges for the equipment designer and manufacturer. The emphasis here will be on the hydraulics, which are in some ways typical of mobile hydraulics and in some ways unusual. We will use the Foster 4200–the largest of the hammers Vulcan produced–as an example.
Basics of Fluid Power
Fluid power is an important component of power transmission for many mechanical applications. Broadly fluid power can be broken down into two parts: industrial and mobile applications. The emphasis here will be on the latter. Most construction machinery manufactured today has some hydraulic control or power included in the equipment. The original vibratory hammers, designed and produced in the then Soviet Union, were electric, but with the introduction of hydraulic vibratory drivers in the 1960’s today most are hydraulic.
The concept behind fluid power is simple:
A flow of fluid is pressurised.
The fluid is delivered to where it is needed.
The fluid does its work, and is depressurised in the process.
The fluid, at or near atmospheric pressure, returns to where it is pressurised.
The process is repeated.
Since the hydraulic fluid being used (petroleum-based, plant-based, or even water) is virtually incompressible, considerations such as occupy students of thermodynamics are not an issue here, although they appear in other parts of the hydraulic system. The power being delivered at any point by a fluid power system is the product of pressure and flow, thus
where is the horsepower being delivered by the fluid, is the gauge pressure of the fluid in pounds per square inch, and is the flow rate in U.S. gallons per minute.
Both the flow and pressure of the fluid are generally delivered by pumps. Fluid power is a little different from many pumping applications in that the pumps are almost always positive displacement, to insure the accuracy of the flow and pressure. The pump performs the first step of the process outlined above; if the power is transmitted at the other end in a rotary way, a motor performs the third step. Unsurprisingly hydraulic pumps and motors are basically mirror images of each other; their construction is similar (not necessarily identical) and their operation is similar. There are several types of hydraulic pumps and motors in use; we’ll concentrate on piston motors and pumps for two reasons:
These are what were used in the Foster 4200 and all of Vulcan’s high pressure machinery (more about pressure levels later.)
They’re a little easier to visualise if you’re not familiar with the application.
Let’s look at a cutaway pump/motor.
The large bronze barrel in the centre of the motor has a series of holes in a radial pattern, into which the pistons (those small cylinders with the rounded left ends) are inserted. The plate an an angle to the bronze barrel is the swash plate, which (through the other plates) either drives (motor) or is driven by (pump) the spline at the left end of the motor, which connects to whatever the motor is driving or the pump is being driven by. The angle between the barrel and the swash plate alows the pistons to move in the barrel, much like the pistons in an automobile do. The displacement per piston is given by
where is the displacement of each piston in cu.in., is the cross-sectional area of the piston in sq.in., and is the stroke of the piston in the barrel in inches. The total displacement per revolution of the barrel is obviously
where is the total displacement in one revolution in cu.in./revolution and is the number of pistons.
The flow of the pump or motor is given by
where is the rotational speed of the motor is revolutions/minute. The horsepower output of the motor (or input of the pump) was given earlier. The torque of the motor/pump is
where is the torque of the motor or pump in foot-pounds.
The simplest configuration of a pump or motor is a fixed-displacement. In this the angle between the barrel and the drive spline (or keyway) is fixed and thus the stroke is fixed. This precise flow is an important aspect of fluid power systems, as it regulates the speed of the load, which can be rotational or translational.
However, there are good reasons for varying the displacement–and thus the flow output–of a hydraulic pump. The pump shown above has a mechanism on the right which varies the position of the right end of the barrel, and thus the displacement of the pistons. Although it’s possible to vary this control manually, the mechanism shown does so by measuring the pressure of the hydraulic fluid, and thus is referred to as pressure-compensated. We’ll come back to why that’s important later.
One further thing that complicates the equations above is leakage around the pistons. Because of the speed of their movement, most piston pumps and motors–and for that matter most hydraulic motors, pumps and valves–do not use seals in them, but tightly fit the pistons or valve spools to the barrel or valve body and allow some leakage. Although this may seem inefficient, the small oil flow allows for lubrication of the components and cooling of the pumps and motors without the drag that seals would induce. This reduces the flow available for power transmission, and the ratio of the ideal flow to the flow actually available after leakage is referred to as volumetric efficiency. This can vary for a number of reasons, but for piston motors and pumps such as we are dealing with here a volumetric efficiency of 90% is a good estimate.
The exciter does the work of the system by inducing a vertical, sinusoidal force in the pile, which sinks by its own weight. The eccentrics producing this force are turned by a motor, which is driven by a pump on the power pack through the hoses. The pump in turn is driven by a diesel engine, which is the prime mover of the system. There’s also a clamp to hold the driver to the pile; in reality there are two hydraulic systems, one for the motor and one for the clamp. This allows us to illustrate hydraulic systems with both rotational output (the motor) and translational output through a cylinder (the clamp.)
The 4200 has two motors to drive its eight (8) eccentrics, but in this case only one clamp for sheeting. A hose layout for the exciter is shown below.
The supply hose is the hose which carries the pressurised oil to the motors. The return hose carries the depressurised oil back to the power pack. The case drain hose returns the leakage from the motor (see earlier comments on volumetric efficiency) back to the power pack. In some cases the return hose can be used as a case drain hose, but in this application there is too much back pressure. The two clamp hoses are bi-directional, as we will discuss shortly.
Until 1991 Vulcan purchased its power packs from HPSI, which used an air-over-hydraulic control system. In going to electric-over-hydraulic, Vulcan was more in line with its competition such as ICE and APE.
Older hydraulic systems used several types of transmissions between engine and pumps, including power-take-off (PTO) drives. Vulcan used a direct drive which was basically a thin circular plate which transmitted torque from the engine to the pump shaft. This seriously reduced mechanical inefficiencies in the system.
We can thus see the essential components of the hydraulic system:
Prime mover (4).
Pump to pressurise the oil (6,7)
Equipment to do the work and depressurise the soil (motors, clamp)
Cooling and oil storage (1,15) after oil is returned to the power system.
Pressure in Hydraulic Systems
Fluid power systems are designed to deliver an oil flow at a given flow rate. So what pressure does this come at? This is a key point in fluid power systems: pressure is determined, without any other restrictions, by the load itself. This is true whether the load is rotational or translational, and in this system we have both.
Rotational (Motor) Loads
The main pump (6) is configured to, at maximum displacement, deliver a given flow of oil. This in turn determines the rotational speed of the motor. The power put into the system–a product of the pressure and the flow–varies with the load of the system, and that in turn varies with the pressure. So are there limits to that pressure?
The answer is obviously yes. Hydraulic systems, broadly, divide themselves into two pressure ranges: high and low. Low pressure systems generally have their pressure limited to about 2500-3000 psi, and a wide range of hydraulic systems operate in this range. High pressure systems run around 5000 psi and beyond. Each system has its own standard of components. The Foster 4200, in common with Vulcan’s 2300 and 4600 vibratory drivers, was a high pressure unit.
So how do we limit the pressure? In “classic” systems such as the HPSI power packs Vulcan started with, there was a fixed displacement pump and a relief valve (11). When the pressure reached the system maximum, the hammer would slow down and the excess oil would “dump over relief.” This worked, but it generates a lot of heat, which means that the system’s thermal protection shuts it down in short order.
On this hammer, Vulcan used a pressure-compensated, “load-sense” system, which required a special relief valve which, in turn, informed the pump that maximum pressure had been achieved. The pump would reduce its displacement as described earlier until the flow and pressure were balanced. There was still a relief “just in case” for safety purposes, but much of the dumping over relief was eliminated. This also enabled the operator to slow the hammer down without slowing the engine down, allowing the engine to operate in its best torque range.
Translational (Cylinder/Clamp) Loads
Before we describe the hydraulics, let’s look at what the clamp does. Some types of hydraulic clamps are shown below (from this article.)
Fun fact: Foster started this project using the clamp type (c), which they inherited from the Japanese. This clamp was common when cylinders were not large and the lever action was needed to obtain the force, but these clamps were heavy. Vulcan convinced them to convert to type (b), albeit without the accumulator, which had been a U.S. industry standard for a long time. Vulcan also convinced Foster to adapt an integral clamp cylinder as opposed to the bolt-on types which are still common on American vibratory equipment.
The clamp is simple: the clamp in pressure is applied to the large (head) end of the clamp and the jaws close on the pile, clamping the pile and stopping the cylinder. When driving is finished, pressure is applied to the small (rod) end of the clamp and the jaws open. The speed of the movement either way is computed as follows:
where is the velocity of the clamp in in/min and is the area (head or rod) under pressure, sq.in. Moving cylinders is a common hydraulic operation, one (with the right control system) can be done with great precision. In this case positional precision wasn’t a big deal; the clamp cylinder just needs to go until the pile stops it.
So what happens then? The system “deadheads,” and, with a fixed displacement pump, most everything goes over relief, with the usual heating problems. There are ways of getting around that but here again pressure-compensated pumps are the best answer, going to nearly zero flow when the clamp deadheads.
Another fun fact: In adopting Vulcan’s clamp design, Foster also incorporated Vulcan’s safety check valve in the clamp, which continued pressurisation in the event the clamp hose was cut. Foster also incorporated Vulcan’s interlock that made it impossible to start the hammer until the exciter was clamped to the pile. That’s one reason why a separate hydraulic system is needed for the clamp; another is that full clamp force and pressure is guaranteed, whereas with the pump for the motor the pressure varies.
We’ve covered a lot of ground here. Hopefully you’ve gotten a better idea of what hydraulic systems in general–using a real-life application–are all about. Vulcan’s effort with Foster’s vibratory hammers was a unique one, and probably resulted in the best vibratory driver (if not the most economical to produce) Vulcan ever made.
Yu. V. Dmitrevich, VNIIstroidormash L.V. Erofeev, Stroifundamentservice V.A. Nifontov, Stroifundamentservice D.C. Warrington, Vulcan Iron Works Inc.
This article was originally published in 1993 or 1994. The graphic above shows a 9 kJ unit mounted on an excavator.
Hydraulic demolition hammers mounted on hydraulically powered excavators are becoming increasingly widespread in world practice. They allow the excavators to be used for breaking rock and permafrost, break up large rocks, old foundations and reinforced concrete structures, and other jobs.
Outline of the Machine
Hydraulic demolition hammers are often equipped with hydraulic accumulators in the pressure line and sometimes in the drain line as well (as is the case with the Raymond hydraulic pile driving hammers) to achieve higher efficiency and to smooth pulses of fluid pressure in the hydraulics. Compressed nitrogen is mostly use as the elastic element in these accumulators.
The proposed hydraulic hammers differ from similar machines of leading companies outside of Russia such as Krupp of Germany, Montaber of France, and NTK in Japan. The main difference is in the accumulators the Russian machines have no compressed nitrogen accumulators, but are equipped with hydraulic accumulators having a so-called “liquid spring,” which is a closed volume of hydraulic oil compressed under pressure four or five times the pressure in the hydraulic system. Possible leaks from the inside of the hydraulic spring are compensated automatically when the hammer is switched off. Such a hydraulic accumulator does not need any adjustments and control during operation and its parts can serve as long as the hammer itself.
The main reason this design was chosen relates to the conditions in Russia itself. The temperature gets very cold, down to -60° C under these conditions the rubber in the bladder type gas accumulators will become embrittled in the temperatures common in many parts of Russia. Once this has happened, the bladders will burst and the machine will have to be completely disassembled and the bladder replaced. This operation is tedious enough on a normal construction site it is a greater problem when the job is somewhere above the Arctic Circle in Siberia.
Another specific feature of these hydraulic hammers is that their rams are not integral with the piston but are connected with the latter through a special elastic hinge. All the hydraulics of the hammer are centralized into a separate unit comprising the working cylinder, distribution valve and hydraulic accumulator. The ram can be of any size as required. The weight of the ram is selected so as to provide the impact energy at an impact velocity of no more than 6 m/sec. The weight of the ram is generally double that the the impact tool with other machines, it can be only half. This provides a high impact efficiency and increases the efficiency of the hydraulic hammer as a whole.
The power output of an impact hammer is the product of the impact energy of the hammer and the number of blows per minute. Thus, for the same power output an impact hammer can have either a high number of blows per minute and a low rated striking energy or a low number of blows per minute and a high impact energy. The advantage of the latter condition, however, is that the higher impact energy can be decisive in producing the high impact force levels necessary to demolish the work at hand. This is why these units have demonstrated outputs two or three times as high as those produce by Kone (Finland,), Krupp (Germany,) and have also outperformed those from Ingersoll-Rand.
The efficiency of these hammers is further promoted in breaking permafrost and rocks by the streamlined shape of the tool itself, which permits the operator to sink the whole hammer into the medium to a greater depth than just the length of the impact tool, i.e. a deeper layer than can be broken at one pass. Thus, there is no need to make the tool very long and the hammer can be operated as a lever, tearing large pieces away from the permafrost or rock. Other companies prohibit such handling of their demolition hammers. The strength of the tool and of the hammer body permit such operation in the case of the Russian machines.
Table 1 shows the standard sizes of the hydraulic demolition hammers based on these principles.
Table 1 Specifications for Hydraulic Demolition Hammers
Impact Energy, kJ
Blows per Minute
Hammer Weight, kg.
Ram Weight, kg.
Weight of Impact Tool, kg
Insertion Diameter for Impact Tool, mm
Hydraulic Oil Consumption, l/min
Working Pressure, MPa
Connecting Hose Size, mm
Weight of base excavator, metric tons
Maximum depth of loosening of permafrost or rock per pass, mm
The Size I has been produced in Belarus since 1982 and the Size IV in Russia since 1978. Sizes II and III have been tested as prototypes and are proving to be the most popular sizes. The design of the hammer is patented in Germany, Hungary and Finland.
Hydraulic hammers of Sizes IV and V may be used for driving small piles after some modification.
Description of Design
The hydraulic demolition hammer is mounted onto excavators as an interchangeable tool by means of an intermediate bracket which is secured both to the excavator and to the hydraulic hammer
Figure 1 shows the main parts which constitute the structure of the demolition hammer. The working cylinder (Figure 2) is essentially a body having a heat treated steel sleeve inserted therein, the latter accommodating a piston moving therein. The body of the work cylinder accommodates a check valve and a hydraulic accumulator comprising a piston with a head and rod, a bushing and a fluid spring enclosed in the cavities bored into the body and communicated with each other and with the rod end of the accumulator by means of ports.
Figure 2 Working Cylinder 1) Casing 2) Sleeve 3) Accumulator Bushing 4) Accumulator Rod 5) Piston 6) Check Valve 7) Lid 8) Check Valve 9) Piston Rod
As shown in Figure 3, a plug is provided to let air out from the cavity of the fluid spring when the latter is being filled with the working fluid.
The rod of the hydraulic accumulator is spring loaded. The head end of the accumulator is communicated with the fluid spring through a check valve intended to compensate for leaks from the cavities of the fluid spring when the hydraulic hammer is switched one and off. The work cylinder is closed from the top with a lid.
The impact portion of the hydraulic hammer is suspended from the rod of a piston by means of rubber shock absorbers. These decrease the dynamic loads acting on the rod. The impact portion moves in the guide pipe. Ports are provided in the upper and lower portions of the guide pipe and these intercommunicated by air ducts. With the impact portion moving, air flows freely from one cavity into the other one through the air ducts.
The impact portion delivers by its lower end blows upon the tool, which can move freely downwards for 60 mm along the guide of the axle box mounted on the guide pipe.
Principle of Operation
Looking at Figure 4, the ram, rod and piston are in their initial position, which is resting on the impact tool. The control valve occupies the upper position under the action of a spring mounted under its lower end position. This communicates the rod end of the work cylinder with the pressure line. It also communicates the head end with the drain line of the hydraulic system, the piston of the hydraulic accumulator occupying the upper position.
Figure 4 Operating Principle of Hydraulic Hammer — Beginning of Cycle, Ram in Bottom Position 1) Impact Tool 2) Body 3) Ram 4) Rod 5) Rod End Cavity 6) Piston 7) Check Valve 8) Drain Port 9) Head End Cavity 10) Duct 11) Control Valve 12) Accumulator Piston 13) Drain Line 14) Pump 15) Fluid Spring Cavity 17) Spring
Figure 5 Operating Principle of Hydraulic Hammer — End of Upward Acceleration 1) Impact Tool 2) Body 3) Ram 4) Rod 5) Rod End Cavity 6) Piston 7) Check Valve 8) Drain Port 9) Head End Cavity 10) Duct 11) Control Valve 12) Accumulator Piston 13) Drain Line 14) Pump 15) Fluid Spring Cavity 17) Spring
After the pump is started, the working fluid gets through the valve into the rod end of the working cylinder and the space above the piston of the hydraulic accumulator. As a result of this the impact portion starts accelerating upwards. This forces the fluid from the head end of the working cylinder through the port along the drain line into the tank, whereas the piston of the hydraulic accumulator moves downwards.
Moving on to Figure 5, at the end of the upward acceleration, the piston passes the drain port, as a result of which pressure in the head end of the working cylinder, the duct and above the upper end of the valve rises. Since the area of the upper end of the valve is greater than that of the lower one, the valve moves into the lower position, thereby communicating the head end with the pressure line and the rod end with the drain line.
This is followed by the phase of slowing the ram to a stop in the upstroke, whereby the piston forces the fluid from the head end into the hydraulic accumulator.
After the ram has stopped at the top of the stroke, it starts accelerating downward under both the force of gravity and the fluid pressure on the head end of the piston. After the impact portion has acquired a speed where it outruns the hydraulic pump, the hydraulic accumulator starts to discharge, and its piston moves upwards. At the end of the downward stroke the ram strikes the impact tool, which moves relative to the body of the hammer so the tool can penetrate the soil. Before the blow is delivered, the upper edge of the piston lowers below the check valve, whereby the head end is communicated with the drain line. As a result of this, the pressure in the head end and above the upper edge of the control valve drops down to a value at which point the spring mounted under the control valve can move the control valve upwards.
After this, the cycle can be repeated. Figure 6 shows the hydraulic schematic for the system.
The fluid spring is used in the structure of the accumulator. In this spring the pressure exceeds that in the hydraulic system by as many times as the area of the piston exceeds the area of the rod entering the cavity of the fluid spring.
Possible leaks from the cavity are compensated by the hydraulic system after the pump through the check valve, with the piston being displaced by the spring mounted thereunder.
The hydraulic hammer cannot be started unless it is applied against the work. Without the work being applied against the impact tool, the block head occupies the lowest position and the upper surface of the piston is lowered below the ports through which the fluid gets into the rod end. An attempt to start up the hammer without the hammer applied against the work results in the fluid passing freely over into the tank, and the hammer does not operate.
The hydraulic demolition hammer with fluid accumulator has proven itself both in theory and in practice. It has as rugged and simple design and is capable of performing many kinds of work. It overcomes many of the difficulties of other designs without unacceptable compromises in performance.
The #3 was one of the early (pre-1900) Warrington-Vulcan hammers, along with the #2 and #1. A general arrangement is shown above; specifications are below.
The #3 found itself involved in some important projects, including the construction of the original Panama Canal, as evidenced by the memo below.
The #3 fell out of favour to the larger #2 and #1 hammers (the #2 eventually suffered the same fate) but in 2008 Pile Hammer Equipment brought back the #3 hammer. They made many changes to the hammer, including increasing the ram weight to 2,100 lbs. (a little more than the Panama Canal hammers,) increasing the stroke to 3′, adding cables and other features. The PHE/Vulcan #3 is the newest Warrington-Vulcan hammer, and also one where a Warrington was involved in the design. You can see a general arrangement of the hammer (with specifications) below; more information and availability can be found by contacting Pile Hammer Equipment.
Intellectual-property protection, however, is deeply problematic. Previous agreements reached under US president Barack Obama’s administration could be reconstituted. But the jurisdictional enforcement of breaches is still hopeless.
One possible mechanism is to subject relevant contracts between Chinese and foreign firms to international commercial arbitration bodies in Singapore or Switzerland, designed to deal specifically with the enforcement of IP protection.
In both contracts Vulcan signed with the Chinese for the sale of the 560 hammers and boiler (1981 and 1983,) our agent Amtech wisely included the following provision:
18. SPECIAL PROVISIONS: Arbitration in Sweden or Canada
One thing that has always struck this observer as unwise is the typical American attitude that everything should be everywhere just like it is in the US. Old exporters (and Vulcan certainly had a good track record in that regard) knew better, but our voices have been ignored, especially in the years of US unilateralism following the end of the Cold War. The rise of China, whose view of life is very different from ours, should occasion the revival of a more “multilateral” approach, but such an approach will require a different style of mind than has been exhibited up until now.
No history of the Warrington-Vulcan hammers would be complete without mentioning the 305 and 306 hammers. The primary purposes of these designations was to harmonise them with the way Vulcan had numbered its larger hammers for many years, although these hammers incorporated changes such as cables and the possibility of Vari-Cycle II.
The most important example of these hammers was the 306 built by the new Vulcan Foundation Equipment (which was owned by the Dutch company IHC) in the early 2000’s, shown below. The 306 incorporated the long ram which was used by the later 06 hammers and the 506.
The 305 was supposed to supersede the #1, but in reality it was never built. Nothing can supersede the #1. The general arrangement for that hammer is below. Specifications for both of these hammers are on the general arrangements.