Interchangeable ram diesel pile

A diesel-engine pile driving hammer provided with interchangeable rams for use in a single, outer, cylindrical casing. A large diameter hole or orifice is provided in the casing between a pair of an array of alternate orifices which are capable of being plugged. The larger orifice or alternate orifices provide an air inlet-exhaust port or ports of sufficient dimension to enable all of the exhaust gases of combustion to be expelled in the time it takes a ram of designated weight to travel its upward stroke in the casing and to vary the swept volume of air introduced into the combustion chamber in the casing so that different weight, interchangeable rams may be accomodated in the same outer cylindrical casing to obtain prescribed impact energy values.

BACKGROUND OF THE INVENTION 
1. Field Of The Invention 
This invention relates to a diesel pile driving hammer, and more 
particularly, a diesel pile driving hammer provided with interchangeable 
rams. 
2. Description of the Prior Art 
Diesel pile driving hammers are drop hammers. A ram within an outer 
cylindrical casing is used to contact an anvil connected to a drive cap 
seated on the pile. The initial power to lift the ram is furnished by a 
hoist line carrying the ram upward on a trip block. At the top of the 
start stroke, the ram is released from the hoist line to fall through the 
outer hammer cylinder casing and to successively close the cylinder casing 
intake-air exhaust openings, compress and heat entrapped air which has 
been captured within the cylinder casing between the ram and anvil and 
explode atomized diesel fuel which has been injected and mixed with the 
entrapped and compressed air. The explosion of the fuel mixture of 
entrapped air and injected diesel fuel sends the ram back up the cylinder 
casing, exhausting the spent gases, and commencing a repeat of the cycle. 
The hammer is stopped by interrupting the fuel flow into the cylinder 
casing. During the dropping of the ram, the ram will contact the anvil to 
drive the pile and drive cap as it compresses the fuel mixture, just prior 
to the explosion which drives the ram back up to the top of its stroke 
wherein the cycle is repeated. 
Standard diesel hammers have ram weights varying from one thousand to 
twenty thousand pounds. The theoretical available impact energy delivered 
per blow by a diesel hammer is a function of the the amount of fuel 
introduced into the hammer, the ram weight, and the efficiency of 
combustion within the cylinder. Traditional means of designing impact 
atomization diesel pile hammers to provide different delivered impact 
energy values has been to vary the ram weight and the fuel volume 
introduced into the hammer cylinder. The flight of the ram is the 
indicator of the efficiency of the explosive force at impact, since about 
all of the net energy from the exploding fuel is utilized in propelling 
the ram upward. The net energy of the explosion is thus reflected by the 
ram stroke times the ram weight. Accordingly, to obtain maximum impact it 
is necessary to maintain the proportional geometry of the combustion 
chamber, e.g., to obtain the optimum efficient fuel mixture volume, so 
that the maximum upward flight of the ram is obtained upon the utilization 
of different ram weights. This has been accomplished in the past by 
providing different cylinder shell or casing sizes with rams of different 
weights. 
Relatively recently, the user of pile drive hammers, the foundation 
contractor, has been charged with not only providing a specific delivered 
energy from a hammer used to install pile foundations, but also to provide 
a hammer with its ram weight restricted within a range for a specific 
energy output and pile to be driven. Accordingly, it has become more 
economical to design a pile driving hammer having a single cylindrical 
casing with interchangeable rams of different weights within the specified 
range and to maximize the geometry of the combustion chamber in the outer 
cylindrical casing so as to arrive at the required specific, delivered 
energy from the hammer per blow. Such a hammer also provides for 
considerable investment economy for the user in that all that is necessary 
are interchangeable, different weight rams interfacing with the same 
cylinder and anvil block. The rams used may be of different weight and the 
final compressed air volume and thus fuel mixture may be varied by 
reducing the height of the annulus formed between the bottom edge of the 
ram piston and the top edge of the anvil block at contact, by changing the 
ram and/or piston geometry. Additional control of the fuel mixture may 
also be accomplished at the fuel pump introducing atomized fuel into the 
combustion chamber and by reducing the swept volume of air compressed in 
the combustion chamber at ram-anvil contact, by providing auxiliary, 
alternate, air inlet-exhaust ports at a location lower than the normal air 
inlet-exhaust ports in the outer cylinder casing wall. These auxiliary 
ports can be closed with high strength pipe plugs when not needed, for 
example, when a ram of a lighter weight is used. 
As indicated, one of the design problems in achieving the required impact 
energy per blow for a different ram of heavier weight in the same 
cylindrical casing has been to maintain the proper proportional geometry 
of the combustion chamber for a particular ram weight and thus fuel 
mixture so as to achieve the required flight of the ram during each stroke 
of its cycle. One attempted solution as noted above, was to provide 
auxiliary air inlet-exhaust ports to reduce the swept volume of air 
compressed in the combustion chamber. But, since the inlet ports of an 
impact diesel pile hammer are also the exhaust ports, the ports must also 
provide a sufficient nonrestricted opening to expel all of the exhaust 
gases of combustion in the time it takes the ram to travel its upward 
stroke, which may be on the order of less than 0.35 seconds, while also 
providing a reduction in the swept volume of air introduced into the 
combustion chamber. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention provides such a solution in an 
interchangeable ram diesel pile hammer. Such a solution entails the 
utilization of a single large diameter hole or orifice as an alternate air 
inlet-exhaust port in the outer cylindrical ram casing located above and 
between a pair of the normal array of inlet-exhaust ports. The alternate, 
larger port can be utilized with a heavier and geometrically sized ram. 
All the ports except the large diameter hole are plugged and closed when 
operating the hammer with the heavier ram. Conversely, the heavier ram 
inlet-exhaust port can be left open when using the lighter ram as there 
will be no change in swept air volume with the lighter ram and all of the 
exhaust gases of combustion can be expelled in as an expedient manner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1A-1E illustrate the operation of a conventional single-acting diesel 
pile driving hammer generally designated by the numeral 10. 
The hammer consists of an outer casing or cylinder 12 slidably receiving a 
ram 14 having a head or piston 16 adapted to impact an anvil 18 provided 
with a semi-spherical bore 20 shaped substantially complementary to the 
head of piston 16 of ram 14. Anvil 18 is seated on cushioning material 22 
provided in a pile cap 24 seated on the top of a pile P which is to be 
driven into a foundation. Cylinder 12 is also provided with one or more 
air intake-exhaust ports 26 extending therethrough. A fuel pump 30 
operated by a trip cam 32 is also mounted on the wall of cylinder 12. A 
hoist mechanism 34 including a load line 36 is connected to a trip block 
38 pivotably mounting a lever 40 extending through an elongated slot 42 in 
the wall of cylinder 12 and seated beneath the head of ram 14. The trip 
block 38 is slidable along the wall of outer cylinder 12. 
FIGS. 1A, 1B, 1C, 1D and 1E illustrate the tripping, fuel injection, 
compression-impact, explosion, and top of stroke cycles, respectively, of 
the operation of an open-end, single-acting, diesel, impact pile driving 
hammer. The hammer is initially operated by load line 36. A crane (not 
shown) raises the load line 36 and trip mechanism block 34 so that the 
trip lever 40 is pivoted in slot 42 upon contact with the upper end of the 
slot formed in the wall of outer cylinder 12 to release the ram 14 and 
piston 16 as shown in FIG. 1B. The ram 14 and piston 16 falls downwardly 
through the outer cylinder 12, contacting fuel cam 32, which pivots in the 
direction of the arrow, or in a clockwise direction, as viewed in FIG. 1B. 
Pivoting of fuel cam 32 actuates fuel pump 30 to spray a metered amount of 
atomized fuel through opening 44 into the cylinder between piston 16 and 
anvil 18. The fuel settles in semi-spherical cup 20 in anvil 18. The 
amount of fuel sprayed from fuel pump 30 can be controlled by a suitable 
manual control on the pump. 
As the ram 14 and piston 16 continues to fall, the ram-piston blocks the 
exhaust ports 26, compressing the air trapped between the piston 16 and 
the anvil 18 in cup 20, as indicated in FIG. 1C. This compressed air 
creates a preloading force on the anvil 18, drive cap 24, and pile P. 
Next, the ram 14 and piston 16 strikes the anvil 18 by entering the 
semi-spherical cup 20 and transmits the impact energy to the pile cap 24, 
while splashing fuel into the annular zone around the piston 16 and anvil 
18 where it ignites on contact with the hot, high-pressure air compressed 
by the ram-piston. 
The resultant explosive force drives the ram-piston upward and the pile P 
further downward as indicated in FIG. 1D. On the up-stroke, the ram-piston 
opens the exhaust ports 26 to discharge the hot exhaust gases of 
combustion. The ram-piston continues freely upwardly until stopped by 
gravity. 
Having reached the top of its stroke, the ram 14 and piston 16 drops again, 
repeating the cycles illustrated in FIGS. 1B-1C, inclusive. The operation 
of the pile driving hammer 10 is stopped by manually pulling and 
disengaging the fuel pump cam 32 to preclude further fuel from being 
introduced into the cylinder beneath the piston 16. 
FIGS. 2 and 3 illustrate the actual construction of the pile driving hammer 
10 of the present invention. Comparable elements to those indicated in 
FIGS. 1A-1E, inclusive, are indicated by the identical numerals. In FIGS. 
2 and 3, however, the fuel pump and fuel pump cam as well as the hoist 
trip mechanism have been deleted; it being understood that the operation 
of the pile driving hammer 10 illustrated in FIGS. 2 and 3 is identical to 
that illustrated in FIGS. 1A-1E, inclusive, as far as fuel injection and 
initial starting operation of the hammer are concerned. 
In addition to the elements discussed and described above, the pile driving 
hammer 10 of FIGS. 2 and 3 is provided with vertical cooling fins 46, 
which act as radiators, connected to the outer cylinder casing 12 to 
radiate heat away from the hammer. The pile driving hammer 10 of FIGS. 2 
and 3 is adapted to be provided with interchangeable rams 14 and pistons 
16 integral therewith. This enables the same outer cylinder 12 to be 
utilized with different weight rams so that economically, the impact 
energy delivered by the pile drive hammer may be varied, as required, to 
achieve fuel conservation, different driving forces as necessary, etc., 
utilizing basically the same equipment except for a heavier or lighter 
ram-piston combination. However, when utilizing rams 14 of different 
weight, the volume of swept air required for efficient combustion and the 
time of travel of the upward flight of the ram after impact and explosion 
will vary. The inlet ports of the impact diesel pile hammer 10 which are 
also the exhaust ports must thus provide a sufficient, non-restricted 
opening or openings to assure the introduction of the proper volume of 
swept air for combustion, and must also enable all of the exhaust gases of 
combustion to be expelled in the time it takes the ram to travel its 
upward flight. This time of travel may be on the order of less than 0.35 
seconds, for example. 
It has been empirically determined that when replacing lighter weight with 
heavier weight rams, such as when replacing a two thousand or twenty eight 
hundred pound ram with a thirty-three hundred pound ram, a sufficient, 
non-restricted opening to expel all of the gases of combustion during the 
return stroke of the ram-piston, while enabling the proper swept air 
volume to enter the combustion chamber of cylinder 12 can be achieved by 
providing a single larger diameter hole or orifice 50 in the outer casing 
or cylinder 12 as the air inlet-exhaust port for the heavier weight ram. 
The hole or orifice 50 is located between and above two of the 
inlet-exhaust ports 26 which are normally utilized for the lighter ram. 
During operation of the pile driving hammer 10 with the heavier ram, all 
of the ports 26 are closed or plugged with high strength pipe plugs 56. 
The ram inlet-exhaust port 50 is in communication with an air intake pipe 
52 having an opening or bore 54 therethrough in communication with the 
opening 50. When using the lighter ram, the opening 50 will remain open 
while the plugs in ports 26 are removed. The use of the auxiliary port 50 
renders the pile driving hammer 10 flexible in that different, 
interchangeable weight rams may be used with a single outer casing or 
cylinder 12 and its attendant accessories. Since the single opening 50 is 
at a higher elevation than ports 26, a proper volume of air can be 
introduced through the sole opening 50 and compressed in the cylinder, as 
required, when the heavier ram is used, while enabling all of the exhaust 
gases to be expelled. Conversely, with a lighter ram, all of the ports 26 
and 50 can be open as there will be no change in swept air volume.