Power hammers for driving piling, and the like, free of any complex
valve mechanism likely to require attention and comprising a working
cylinder having an anvil at the lower end thereof and a ram operative
as a piston in the cylinder, cooperative with the anvil and surrounding
walls of the cylinder to form an expansion chamber, the ram having
a passage extending from an annular groove intermediate the ends
of the ram, down through the lower end to the expansion chamber
and the cylinder having pressure supply and exhaust ports to register
with the passage and to be uncovered by the ram, in lower and upper
positions of the ram in the cylinder, whereby the essential functions
of the hammer are automatically effected in the normal operation
of the ram. Pressure controlled valves may be added to automatically
hold desired pressures and release opposing pressures on the ram.
The embodiments of the invention in which an exclusive property
or privilege is claimed are defined as follows:
1. A power hammer comprising:
a normally upright cylinder having a top, an upper portion and
a lower portion;
an anvil at the lower end of the cylinder, the anvil having an
a ram in said cylinder operating in cooperative relation with the
anvil, said ram being movable longitudinally between a lower position,
wherein the ram is against the anvil, and an upper position, wherein
the ram is away from the anvil and adjacent the upper end of the
the ram having an upper end and a lower end, an upper lateral surface
adjacent the upper end and a lower lateral surface located intermediate
the upper end and a lower lateral surface located intermediate the
upper end and lower end of the ram;
a longitudinal passage in the ram passing through the upper end
thereof and a lateral opening connecting the passage with the exterior
of the ram below the lower lateral surface thereof;
a tube carrying a piston valve element positioned within the passage
to register with the opening in the down position of the ram and
enable communication between the interior of the tube and the lower
portion of the cylinder at the lower lateral surface of the ram
in the down position; and
sealing means on said tube for sealing said opening from said passage
until the ram is adjacent the upper position thereof, wherein the
opening communicates with the upper portion of the cylinder at the
upper surface of the ram, through said passage while, at the same
time, connecting the passage with the exterior of the ram below
the lower lateral surface thereof;
said upper surface of the ram having a larger area than the lower
surface of the ram.
2. The invention of claim 1 wherein said sealing means include
a sleeve and sealing rings on the tube.
3. The invention of claim 1 wherein the tube is mounted in the
top of the cylinder.
4. The invention of claim 3 including a motive fluid chest at the
top of the cylinder and wherein the tube communicates with the chest.
5. The invention of claim 1 wherein the ram includes an upper head
portion and a lower striking portion, the head portion having a
larger diameter than the striking portion.
6. The invention of claim 5 wherein the head portion and the striking
portion are assembled from separate parts.
The present invention relates generally to power hammers and pertains,
more specifically, to power hammers for driving piling and known
as pile hammers.
Generally stated, objects of the invention are to provide a pile
hammer of simple, sturdy construction, which could be produced at
reasonably low cost, which would have greater power output and speed
of action than pile hammers of conventional design, which would
be controllable to meet existing operating conditions, and which
would be practical in all respects.
The accompanying drawing illustrates certain present practical
embodiments of the invention, but the structure may be further modified
and changed, as regards to the immediate illustration, all within
the true intent and scope of the invention, as hereinafter defined
and claimed. In the drawing:
FIG. 1 is a longitudinal cross-sectional view of one of the pile
hammers constructed in accordance with the invention, with the ram
shown at the bottom of its stroke, in engagement with the anvil
and closing the exhaust port in the side of the cylinder;
FIG. 1A is a fragmentary view of the upper portion of an alternate
FIG. 2 is a view similar to FIG. 1 but showing the ram at the
top of its stroke, in position opening the exhaust port;
FIG. 3 is a longitudinal cross-sectional view of the ram;
FIG. 4 is a cross-sectional view of the ram taken along line 4--4
of FIG. 3;
FIG. 4A is a cross-sectional view taken along line 4A--4A of FIG.
FIG. 5 is a cross-sectional view similar to FIG. 1 showing automatic
pressure control valves added at opposite ends of the cylinder;
FIG. 6 is a like cross-sectional view showing a pressure control
valve seated in the upper end of the ram;
FIGS. 7 and 8 are enlarged fragmentary cross-sectional views of
the upper and lower control valves shown in FIG. 5;
FIGS. 9 and 10 are cross-sectional views illustrating a "double-acting"
pile hammer constructed in accordance with the invention;
FIG. 11 is a cross-sectional detail of a "choke" form
of pressure control;
FIG. 12 is an enlarged cross-sectional detail of the piston valve
appearing in FIGS. 9 and 10;
FIGS. 13 and 14 are cross-sectional views of a "compound"
pile hammer constructed in accordance with the invention;
FIG. 14A is an enlarged detail of a control valve in the hammer
of FIGS. 13 and 14;
FIGS. 15 and 16 are longitudinal cross-sectional views of a convertible
form of the pile hammer, designed to operate, for example, as a
single action, 36 inch stroke, 80 blows per minute hammer, or as
a double-acting 18 inch stroke, 100 blows per minute hammer;
FIGS. 17 and 18 are longitudinal cross-sectional views of a "single-acting"
pile hammer employing a control valve in the passage of the ram;
FIGS. 19 and 20 are longitudinal cross-sectional views of another
single-acting pile hammer in which a choke control valve, similar
to that of FIG. 11 is employed to cushion the drop of the ram;
FIG. 21 is an enlarged fragmentary cross-sectional view of a valve
element of the hammer of FIGS. 19 and 20.
FIGS. 1 to 4 show a pile hammer constructed in accordance with
the invention and including a working cylinder 20 of uniform diameter,
and a companion uniform diameter ram 21 operating as a piston therein,
in cooperative relation with an anvil 22 closing the lower end
of the cylinder.
The ram is specially designed to operate as a valve maintaining
the essential functions or phases of the pile hammer. Thus, the
ram is shown as having a central bore or passage 23 extending from
the top, down through the bottom of the ram and a shallow annular
groove 24 in the side of the ram, intermediate the ends thereof,
in communication with the bore, by equally spaced radial ports 25.
The bore may be a central or off-center passage, functioning as
it does, as a conduit for the motive fluid which usually is steam
or compressed air. The ram is shown in FIGS. 1 and 2 closed at
the top by a cover plate 26. The ram and the anvil are sealed in
the cylinder, as by piston rings, indicated at 27 and 28 forming
cooperatively an expansion chamber 29 beneath the lower face of
Motive fluid is supplied under pressure from a chest 30 surrounding
the cylinder, having a plurality of equally spaced ports 31 in
the cylinder, placed to register with the groove in the side of
the ram, when the ram is at or about the lower end of its stroke.
An exhaust port 32 in the side of the cylinder, is positioned to
be covered by the ram in the lower portion of its stroke, as indicated
in FIG. 1.
In operation, motive fluid passes from supply chest 30 through
ports 31 into the groove 24 in the ram, with the ram in the lower
portion of its stroke, and thence through radial ports 25 into
the passage 23 to the expansion chamber 29 beneath the ram, so
as to raise the ram. Cutoff is determined by passage of the grooved
portion of the ram above the inlet ports 31 as in FIG. 2 and exhaust
is effected when the sealed lower end portion of the ram over-reaches
the exhaust port 32 in the cylinder.
In the variation illustrated in FIG. 1A, upward movement of the
ram is facilitated by ports 32' which are open to the ambient atmosphere
and relieve any back pressure in the upper portion of the cylinder
as the ram rises. These same ports 32' will prevent vacuum buildup
and consequent retardation of the ram during the downstroke thereof.
In FIG. 5 the hammer is shown equipped with pressure-operated
automatic valves 33 and 34 with connections 35 36 to opposite
ends of the cylinder. These valves are alike in that they are each
spring-opened and pressure-closed. Thus the upper, upwardly faced
valve 33 as shown in detail in FIG. 7 is in the nature of a one-way
check valve or poppet valve, having a conical valve member or element
37 held seated in closing position by pressure in the cylinder
connection 35 and sustained in open relation by spring 38.
The upper valve, shown in FIG. 7 will thus stand open to atmosphere
on down travel of the ram to prevent vacuum buildup and retarding
effect on downstroke of the ram and will remain thus open until
pressure generated on return stroke of the ram becomes sufficient
to overcome the valve-opening spring force. This vacuum relief valve
thus promotes full live action of the ram and buildup of a cushion
and pressure source at start of the downstroke.
The lower valve 34 as shown in FIG. 8 opens downwardly, with
the spring 39 holding it open to atmosphere to relieve back pressure
on the downstroke of the ram. When sufficient pressure builds up
beneath the ram, this valve closes, in readiness for the next upstroke
of the ram. The release of pressure, upon opening of exhaust port
32 enables opening of the back pressure relief valve, as shown
in FIG. 8 in proper timed sequence. These control valves facilitate
and contribute to the full power development and speed of the hammer.
FIG. 6 shows how an automatic back pressure relief valve 40 similar
to that shown in FIG. 8 may be incorporated in the head of the
ram, seated in the upper end of the bore 23 left open in this case
to receive the valve. Valve 40 closes upwardly by pressure admitted
to the bore at start of the upstroke of the ram and opens to atmosphere
to relieve back pressure on downstroke.
In the double-acting form of the hammer shown in FIGS. 9 and 10
a tube provides a valve inlet stem 41 and is supported in the head
of the cylinder, stem 41 carrying piston valve elements 42 43 spaced
to register with the feed groove 24 in the ram, in the down (FIG.
9) and up (FIG. 10) positions of the ram. A back pressure relief
valve 44 similar to that shown in FIG. 8 is provided in motive
fluid connections 45 46 to the lower portions of the cylinder.
Thus, motive fluid enters stem 41 and passes through lower valve
element 43 (also see FIG. 12) and motive fluid connections 45 46
to the lower portion of the cylinder to raise the ram from the lower
position, seen in FIG. 9 to the upper position, seen in FIG. 10.
In the upper position, passage 23 of the ram seals the lower valve
element 43 and motive fluid passes through upper valve element 42
and into the upper portions of the cylinder to drive the ram downward.
FIG. 11 shows how a pivoted choke 47 may be incorporated in a control
valve 48 which is otherwise similar to that shown in FIG. 8 with
a remote control operating piston 49. The purpose of this choke
is to retard or vary energy output by increasing back pressure.
In the compound type of hammer shown in FIGS. 13 and 14 the ram
21 carries a larger diameter piston head 50 operating in a larger
diameter cylinder extension 51. A control valve element 52 (also
see FIG. 14A) is placed in the longitudinal passage 53 between opposite
ends of the combined ram and piston head 50 and a valve 54 similar
to that shown in FIG. 7 is connected with the upper end of the
upper cylinder 51. Motive fluid passes from the chest 51' at the
top of the cylinder extension 51 through tubular stem 41 valve
element 52 and lateral ports 25 into the cylinder extension beneath
piston head 50 to raise the piston head and the ram from the lower
position, shown in FIG. 13 to the upper position, shown in FIG.
14. At the upper position, the valve element 52 is closed, but the
partially expanded motive fluid passes from beneath the piston head
50 through the passage 53 into the cylinder extension above the
piston head 50 to drive the piston head and ram downward. Valve
54 remains open by virtue of spring pressure during the upstroke
and then closes, in response to the pressure of the motive fluid,
for the downstroke. The valve element 52 has an extended sleeve
52' and sealing rings 52" which close and seal the passage
53 to the passage of motive fluid from beneath the piston head 50
to above the piston head until the upstroke is nearly completed.
Sealing rings 53' seal the motive fluid from passage 53.
It is noted that the higher pressure motive fluid beneath the piston
head 50 acts upon the smaller annular area of the piston head between
the ram and the cylinder, while the lower pressure, partially expanded
motive fluid acts upon the larger area of the top of the piston
head. In this manner full advantage is taken of the ability of the
motive fluid to expand as much as possible. Upon completion of the
downstroke, the motive fluid is exhausted through port 32"
and the cycle can be repeated. The location of chest 51' immediately
above cylinder extension 51 enables heat from a heated motive fluid
to maintain the cylinder extension at a higher temperature. The
cylinderical portion 29' within which the striking portion of ram
21 operates is isolated from the working cylinder extension 51 by
piston rings 27 and 27', thereby enabling simplification of the
design of the anvil area. The two-part ram 21 and head 50 enables
economical manufacture, utilizing appropriate materials for each
part. Thus, the head 50 can be fabricated of inexpensive cast metal
while the smaller ram 21 can be made of high quality steel for withstanding
the necessary striking forces. The separate parts are then joined
into an integral ram, as by a press-fit at 21'.
FIGS. 15 and 16 show how the hammer may be built in a "convertible"
form, to operate as a single-acting, slower and longer stroke hammer,
or as a double-acting, faster and shorter stroke hammer.
A spring-loaded, normally open control valve 55 similar to that
in FIG. 8 is connected with the expansion chamber 29 and a second
exhaust port 56 is spaced above the first exhaust port 32 to be
uncovered in the longer stroke operation of the ram.
The pressure supply line 57 is branched at 58 into the top of the
cylinder above the ram and is provided with a pressure-regulating
valve 59 and with an on and off ball valve or equivalent control
60 above valve 59. An upper cylinder vacuum relief valve 61 similar
to that in FIG. 7 is connected into the upper end of the cylinder
The lower short-stroke exhaust port 32 may be closed by insertion
of a plug, or by closing off the port with a valve, when operating
as a slower, longer stroke hammer, with the ball valve closed and
using the upper exhaust port 56.
The convertible form of the hammer provides an extensive choice
of speeds and energy output. Without an upper cylinder compression
and vacuum relief valve 61 the hammer may operate, for example,
with a 4-foot stroke and a speed of 50 to 55 blows per minute. With
an upper cylinder compression holder and vacuum relief valve 61
in place, this hammer may, in the example, be run at a speed of
80 blows per minute on a 3-foot stroke, in the single-acting mode.
With the lower exhaust port 32 open to atmosphere, the ball valve
open, inlet pressure at 100 psi, and a constant down pressure on
the upper face of the ram reduced by regulating valve 59 to, say,
40 psi, the hammer will operate with an 18 inch stroke, at 100 blows
In FIGS. 17 and 18 there is illustrated a single-acting version
of the hammer illustrated in FIGS. 9 and 10. Here, motive fluid
is passed through tubular stem 41 and valve element 43 and then
through motive fluid connections 45 46 to expansion chamber 29
to raise the ram from the lower position, shown in FIG. 17 to the
upper position, shown in FIG. 18. Upon opening of chamber 29 to
atmosphere, through port 32 the ram will drop freely from the upper
position to the lower position. Upward movement of the ram is facilitated
by ports 32' which are open to the ambient atmosphere and relieve
any back pressure in the upper portion of the cylinder as the ram
rises. These same ports 32' will prevent vacuum buildup and consequent
retardation of the ram during the downstroke thereof.
Turning now to FIGS. 19 through 21 another single-acting hammer
is shown. Motive fluid is supplied from chest 30 and passes through
valve element 42 carried by stem 41 to the expansion chamber 29
to lift ram 21 from the lower position, shown in FIG. 19 to the
upper position, shown in FIG. 20. A back pressure valve 48 similar
to that of FIG. 11 is affixed to the stem 41 and includes a choke
for softening or cushioning the blow of the ram in the downward
stroke, by virtue of the control of the back pressure which will
build up beneath the ram during the downstroke. Alternately, a back
pressure valve, similar to that of FIG. 8 can be placed in stem
41 in place of valve 48.
In all forms of the invention, ample clearance for the entering
motive fluid is provided, assuring quick immediate action.
The lower face of the anvil is shown with cross V-grooves 62 (see
FIG. 4A) providing instant access of entering live steam or compressed
air to the lower lifting area of the ram.
By reversing the hammer, end for end, and providing pile attaching
means, the hammer may be used as a pile extractor.
The choke added to the exhaust back pressure valve 48 in FIG. 11
is shown as a simple choke plate which can be closed by a compressed
air or steam motor 49 to create back pressure in the lower cylinder
for softening or cushioning the blow of the ram.
All forms of the hammer are of simple, sturdy, low-cost construction.
Clearance volume to provide room for air compressed ahead of the
descending ram may be provided by closed end tubes connected with
the expansion chamber as shown at 63 in FIG. 15 or by chest 64 surrounding
the expansion chamber and open thereto by ports 65. No ports 65
are present in the hammer of FIGS. 19-21.
Rest position of the ram and start and finish of stroke may be
governed to a desirable extent by the number of steel and shock
absorbing spacing shims 66 used between the anvil and the end of
the cylinder. No "cushion block" is required. The piston
rings 27 located at opposite ends of annular groove 24 are spaced
apart a sufficient distance to enable repositioning of the ram by
the addition or subtraction of spacing shims 66 to vary the start
and finish of the stroke of the ram without changing the mode of
operation of the hammer. Thus, the spacing shims 66 provide means
for selectively varying the location of the lower position of the
ram relative to the cylinder to control cutoff, or duration of motive
fluid inlet. The more spacing shims 66 inserted, the longer the
duration of inlet, the greater is the amount of motive fluid energy
introduced into the expansion chamber and the higher the ram will
be lifted. Such a means for control is advantageous in changing
from one motive fluid to another. That is, different inlet durations
should be used with heated air at different temperatures, while
a still different duration would be more appropriate for saturated
The hammer forms a compact unit free of objectionable valve or
other projections and may be operated underwater as well as on dry
The hammer may be made self-stopping by lowering the anvil below
the point of registration of ram inlet slots with the cylinder inlet
The controls illustrated enable the hammer to be adjusted to meet
many different or changing operating conditions.
It is to be understood that the above detailed description of an
embodiment of the invention is provided by way of example only.
Various details of design and construction may be modified without
departing from the true spirit and scope of the invention as set
forth in the appended claims.