CA1054027A - Fail safe fluid power device - Google Patents

Abstract

FAIL SAFE LIQUID POWER DEVICE

Abstract of Disclosure The present invention relates to a fluid power device such as one for opening and closing clam shell gates and operated by a ram under fluid pressure. A tank is provided for storing fluid under pressure and by a system of valving, extension of the ram, as for a gate opening operation,it is inhibited until enough fluid under pressure is stored in the tank to assure completion of reverse operation of the ram to close the gates.

Description

~59~ 7 The present invention relates to a fluid power device SUCll for example as one for opening and closing clam shell gates and operated by a ram under fluid pressure.
The device makes use of a fluid actuated ram for S doinc~ work, customarily referred to as a hydraulic ram. A
commercial construction device usually manipulated by employ-rnent of such a ram consists of clam shell gates such as are used on concrete placement buckets. Another consists of a ,~!.
pair of hooks such as are used by cranes for lifting and placing construction material. These however are merely examples in that the reciprocating action of a ram may be adapted to a great assortment of uses.
A popular pneuma-tic gate actuating device for con-crete buckets may be found disclosed in U.S. Patent No.

2,856,222, which makes use of a portable air pressure res-ervoir for the purpose of manipulating a ram. A more recent gas actuated power device is found disclosed in U.S. Patent No. 3,104,125 where a portable gas pressure device is coupled with mechanisms capable of operating semi-automatically.
Although devices of the kind disclosed in the ~:
patents mentioned have long been effectiva~ there has been a noteworthy shortcoming in that there is no assurance after a palr of clam sheel gates for example, have been opened, that there is enough air pressure left to completely close them. Gauges and the like of course can be made use of but such expendients are always subject to human error. When for example, a large bucket of wet concrete has been opened or perhaps partially opened for dumping ~he load, inability to promp ly and effectively close the gates before dumping the entire load could be extremely disadvantageous, causing ~i~5~
wet concrete to be d~ ed in the wrong place. Inability to disengage a hook could be equally disadvantageous.
It is therefore amony the objects of the invention to provide a new and improvecl fail safe fluid power device of a reciprocating character wh~re operation in one direction is inhibited until there is assurance that operation in a reverse direction can be run to oompletion once operation in a forward direction has been undertaken.
Another object of the invention is to provide a new and improved fail safe fluid power device which is completely portable and which auto-matically assures a complete reciprocating cycle of the ram prior to initi- ~ ~`
ation of operation.
Still another object of the invention is to provide a new and improved hydraulic ra~ system operating under liquid pressure wherein adequate pressure and v~lume must ke stored to complete a reverse operation ` prior to initiation of a forward operation and wherein there is an overload ; relief capable of preventing strain on the system should forward operation be interrupted for any reason.
With these and other objects in view, the invention provides, accordIng to one aspect thereof, a system for performing work by operation - 20 of a hy~raulic ram having a piston therein forming in the ram a forward cha~ber and a reverse chamber, the system comprising a source of fluid at -` forward operating pressure, a fluid pressure storage container including fluid passage means connecting the container to the source, and operating valve means having fluid passage means connecting the operating valve means respectively to the source, the container and the ram for selectively ; directing fluid at the forward operating pressure to the forward chamber.
The operating valve means has one adjustment wherein the forward operating pressure is passed to the forward chamker and the reverse chamber has a ~ ~ ;
connection to exhaust. Sequence valve means are connected respectively to the container, the source and the operating valve means. The sequence valve means has an adjustment at press~es less than the forward operating pressure which inhibits passage of fluid by the operating valve ~.eans to - - . ~

the forward chamber until the container is at the forward operating pressure.
The operating valve means has another adjustment connecting the ~orward cl~amber to exhaust, and a fluid connection is provided bet~-een the containex and the reverse c~amber operative to reverse action of the ram when the fon~ard chamker is connected to exhaust.
According to another aspec-t of the invention a system Eor per-forming w~r]s by operation of a gas actuated ram comprises a cylinder and a piston therein forming in the cylinder a ~orward chamber and a reverse chamber, wherein the reverse cha~ber has a reverse exhaust means at a pres Æ e exceeding ambient pressure, and wherein the piston is movable between full forward and reverse positions. The system comprises a source of gas at forward operating pressure, a gas storage container means of capacity at least equal to the capacity of the reverse chanber with the piston at full reverse position, the container means including gas passage means connecting the container means to the source~ Operating valve means are provided, cc~prising a forward acting member and a forward exhaust member, the forwarl acting member including gas passage means interconnecting the source, the container means and the forward chamker, the operating valve means having one adjustment wherein the forward acting memker is in a posi-tion wherein the source is connected to the forward chamber ~or passing gas at forward operating pressure to the forward chamber and wherein the reverse chamber has a connection to the reverse exhaust means. Sequence valve n~ans is interconnected with the cont~iner means and the operating valve means, the sequence valve means having a first automatic adjustment at pressures less than the forward operating pressure operative to inhibit . .
passage of gas by the operating valve means to the forward chamber. The sequence valve means has a second automatic adjustment when the container means is at forward operating pressure. The operating valve means has another adjustment in response to the second automatic ~djustment of the sequence valve means wherein the forward exhaust mem~er connects the forward chamber to exhaust and the source is disconnected ~rom the forward chamber.
A gas connection is provided between the container means and the reverse .. , .~ .
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5~27 cha~ker, the last mentioned connection bein~ operative to pass gas under pressure to the reverse chamber whereby to reverse action of the ram when t~le forwarcl chamber is connected to exhaust.
In the accompanying drawings, which illustrate emkcdLments of the invention;
FIGURE 1 is a schematic representation of one form oE the device ~hich n~kes use of gas pressure, applied to t*~in rams operable at opposite ends of a pair of clam shell yates.

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.''` ' ~ - 3b -105~7 FIGURE 2 is a schematic representation of a second ; form of the system making use of air pressure.
FIGURE 3 is a longitudinal sectional view of a typical quick exhaust valve usable with the system of Figure 1.
FIGURE 4 is a schematic representation of the sys-tem in a form capable of using liquid under pressure.
In one embodiment of the invention chosen for the purpose of illustration there is shown a pair of clam shell gates indicated generally by the reference character 10 manipulated at one end by a fluid actuated ram 11 and at the other end by a fluid actuated ram 12. The ram 11 is pro-vided with a piston 13 and piston rod 14 which performs the workr namelv, opening and closing gates 15 and 16 by use of ;
the mechanism 17. The piston 13 separates the ram into a forward acting chamber 18 and a reverse acting chamber 19/
the forward acting chamber being one which under power opens the gates and the reverse acting chamber beiny one which under power closes the gates. The ram 12 is similarly equip-ped and operates a mechanism like the mechanism 17, not `~
~i shown, attached to the opposite ends of the gate. On occa-sions one ram only may be employed.
A supply of air pressure 25 from an outside source ~ is accepted by a selector valve 26. There is a similar sup-- 25 ply 27, normally on the opposite side of the concrete bucket ~` where the device is one set up to manipulate the clam shell `~ gates. Air from one or another of the supplies after passing to the selec-tor valve 26 travels through a strainer 23 and an air passage 29. From the passage 29, depending on the condition of the system, ai~ will travel either through an '' ' ' ' , ' ' '"' :, ` ' . ' ~.;
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air passage 30 to air receivers 31 and 32 or through air passage 33 -to a two-way two position pilot operated valve 34. ~ c'heck valve 35lallows passage to the air receivers but blocks air traveliny from the receivers.
From the pilot operatecl valve 34 air is adapted to travel both through an air passage 35 to the ram 11 and an air passage 36 to the ram 12. ~cting in conjunction with the ram 11 is a quick exhaust valve 37 in the air passage 35.
A similar ~uick exhaust valve 37 accommodates the ram 12 and is in the air passage 36.
Connected to the air receivers is a sequence valve means 40, and a pilot line.41 connects the sequence valve 40 means with the pilot operated valve 34.
':~ To complete'the fluid pressure loop air passages ', 15 42 and 43 leading respectively to the reverse acting chambers 19 of the rams 11 and 12 are connected to the air receivers 31 and 32. Actually there is provided a line 44 from the ~. air receiver 31 and a line 45 from the air receiver 32 which ~.
-.~ join a common air passage 46. In the air passage 46 is a .' 20 pressure relief valve 47, a pressure regulator 48 and a ~
' check valve 49, the check valve 49 being oriented to permit : , .
~ flow to the rams but prevent flow from the rams.
'-', In operation of the system as shown in Figure 1 ~ let it be assumed that the pressure of the air supply 25 is .. . . . .
60 pounds per square inch'with the selector valve 26 moved ' . to accept the air under pressure and pass it through the air ~, passage 29~ In the position of adjustment shown in Figure 1 -~, d,~, passage of air is blocked by adjustment of the pilot valve .
34, consequently, air at the selected pressure passes through '~
the air passage:30 past the'check valve 35' and i.nto the air . ':~
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receivers 31 and 32. By setting the sequence valve means 40 to a pressure of 60 pounds per square inch the sequence valve means will maintain the pilot line 41 closed until .
both air receivers are pressurized to 60 pounds per square inch. At that point the sequence valve means will pass air under pres.sure to the pilot operated valve 34 causing it to assume a second position of adjustment which permits air to flow from the air passage 33 to the air passage 35 and 36 and to the for~ard acting chambers 18 of the respective rams 11 and 12. As a consequence, the pistons 13 are moved down-wardly in a direction causing the gates 15 and 16 to open.
During this portion of the cycle air pressure for example in the air passages 35 and 36 flows through a p.ilot line in the respective quick exhaust valve 37 to adjust the valve to the . 15 position shown in Figure l so that there is flow of air under .~ pressure to the forward actin~ chamber of each of the rams ll and 12.
. When the gates are to be closed a reverse movement is necessary. To accomplish this air pressure in the air passages 35 and 36 is cut off by disconnecting the supply of ~:
. air at 25 or 27. ~hen this happens a change in air pressure . in the pilot line 50 causes a shift in adjus-tment of the . quick exhaust valve to a second position wherein the forward acting chamber l~ is vented to exhaust and air flow in the ~ 25 air passages 35 and 36 is blocked.
: Simultaneously, air from the air receivers 31 and ~A", 32 at 60 pounds per square inch is converted to air pres- :
sure at 18 pounds per square inch for example by operation of the pressure regulator 48. The specific pressure is some- :
what optional, 18 pounds pe~ square inch being merely by way ' ~

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10~ 7 of example. Under such circumstances the pressure relief valve 47 is set at a pressure higher than that of the pres-sure regulator, 20 pounds per square inch for example in the chosen illustration. As a consequence, air at 18 pounds per square inch passes the check valve ~9, canno-t be vented through the pressure relief valve 47 and therefore flows through the respective air passages 42 ancl ~13 to the reverse acting chc~mber 19 of each of the rams 11 and 12, causing the piston 14 to move up~ardly to close ~he gates 15 and 16.
Closing can be stopped at any point prior to com-plete closing by merely again manipulating the selector valve 26 to introduce air under pressure to the air passages 35 and 36 which will change the adjustment o the quick exhaust ' ` valves and again pressurize the forward acting chambers 18.
Since air pressure in the forward acting chambers 18 is al-ways at the higher pressure namely, 60 pounds per square inch, in the example chosen, the pressure differential on ~` opposite sides of the piston 13 will be 42 pounds and the piston can be moved in the chosen direction despite the pre- ' sence of air at 18 pounds per square inch pressure in the return chamber 19. As the piston continues to move expelling air from the return chamber 19 at 18 pounds per square inch, i ,~
- pressure is built up to 20 pounds by reason of the setting of the pressure relief valve 47 and the air is exhausted by the pressure relief valve at the 20 pound pressure thus per-,~ mitting the piston to continue its travel. ~ ,-In the embodiment af the invention of Figure 2 ~;
presence of the quick exhaust valve is dispensed with and a ,different type of pilot operated valve 54 is made use o. ''~ ~' ~30 In this example also only o~e air receiver 55 is employed.

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~5~27 In the operation of the system set up in this fashion, prior to the time when the sequence valve means 40 indicakes pres-sure in the air receiver 55, to be less than 60 pouncls per square .inGh, in the example chosen, air under pressure fxom the source 2S is blocked by the adjust.ment shown of the pilot operated valve 54. When the air receiver has been pres-; surized to 60 pounds per square inch the sequence valve mem-ber 40 will communicate with the pilot operated valve 54 through the pilot line 41 causing it to assume a new adjus-t-ment wherein air in the air passage 33 is passed directly to the air passages 35 and 36. This means that the forward acting ch~nbers 18 are pressurized causiny the pis-ton 13 and piston rod 14 to move downwardly in the illustration as shown.
:` 15 Conversely, when the piston is to be moved in the .
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opposite direction the source of air pressure at 25 is dis~
continued allowing such connection as i5 provided to exhaust directly -to atmosphere. This means that simultaneousl~ air in the respective forward acting air chambers 18 will be ; 20 vented through the pilot operated valve 54 and air passages 33 and 29 to atmosphere through the selector valve 26. Mean-while air which has accummulated in the air receiver 55 .:
passes through the line 44 to the pressure regulator 48 . where the pressure is reduced to 18 pounds per square inch, --, 25 and air under the new lower pressure passes the check valve : 49, bypasses the pressure relief valve 47 and travels through the air passages 42 and 43 to the reverse acting chambers l9 of the respective rams ll and 12 As air is consumed in moving the piston in the reverse dir~ction the pressure in the air receiver 55 may `:

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~54Q27 fall below the sequence valve 40 setting, in this example 60 pSi. If that should happen, pilot operated valve 54 will shift back to its original position allowing air to flow from lines 36 and 35 through the valve and out to the atmos-phere, allowing the reverse action to continue.
When the rams have become completely closed or should closing of the rams be stopped at any point ~he re-verse acting movement is stopped in the same manne- as has been previously indicated, namely, by applying air under pressure again from the source 25 to the selector valve 26 ~:
to repressurize the forward acting chambers 18. Whenever there is movement of the piston downwardly in the chosen . example air from the reverse acting chambers 19 is vented through the pressure relief valve 47 which is set at a pres- :
sure slightly higher than the pressure of the pressure regu-::
lator 48.
.` In both forms of the system as shown in Fiyures 1 ~ ::
and 2 there is provided a constantly open vent 56 which is in communication with the pilot line 41 and sequence valve means 40 where~y ultimately to reduce pressure in the pilot -:: line 41, when the sequence valve no longer supplies air to. ~ -line 41 due to the pressure in the air receiver falling be- ~.
low the preset sequencing pressure (60 psi), causing the . pilot operated valve 34 or 54 as the case may be, to re~
: 25 assume initial position, namely, a position that exhausts ~:
the forward acting chambers 18 and redirects any newly ap-plied air pressure to the air receiver, blocking its flow through the pilot operated valve.
A typical quick exhaust valve suited to the system is one shown in Figure 3, identified by reference character .,, :.
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37'. In a valve of this description when the forward acting chamber is to b~ supplied with air under pressure air flows from the air passage 35 to a location above a double acting ~lexible diapllragm 57. Since the edge of the diaphracJm is flex:ible the edye is permitted to deflect to allow air under presC;ure t3 travel through an inside passage 58 and from there to the air passage 51 which supplies the forward acting chamber 18.
When air pressure is discontinued in the air pas-sage 35 and movement of the piston 13 reversed air flow is reversed in the air passage 51 and inside passage 58 the e~-fect of which is to shift the position of the diaphragm up-wardly to a location where flow is blocked into the air pas-sage 35. ~ovement of the diaphragm blocking the air passaye lS 35 at the same time opens flow to the exhaust 52 and in this - way the forward acting chamber 18 is immediately and quickly exhausted.
In the arrangement of the system as shown in Fig-ure 4 to which this divisional application is directed where liquid hydraulic fluid is employed, use i5 made of a gas charged hydraulic accummulator 60 as a container. The accum-mulator includes a gas chamber 61 and a liquid chamber 62 ; s~eparated by a flexibls diaphragm 63. Hydraulic liquid is ` contained in a reservoir 64 from which it is drawn through a - 25 strainer 65 by a pump 66 operated by a motor 67. Liquid at pump pressure is passed through a liquid line 68 to a se-quence valve means 69 then through a liquid line 70 and three~way two position control valve member 71, through an--` other liquid line 72 to the liquid chamber 62 to the accum-mulator. The control valve member 71 is operated by means - . :

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of a solenoid 73 and by action oE a sprins 74. With power to the pump motor 67 on, the valve assumes the adjustment shown in Figure 4 where the liquid passage is open from the source to the accummulator 60.
~lso in communication with ~he sequence valve mealls 69 through a liquid line 75 is a four-way three posi-tion control valve member 76. Solenoids 77 and 78 accom-panied by springs 79 and 80 are employed to manipulate the control valve member 76.
A liquid line 81', 81 provides communication be-; tween the control valve member 71 and a liquid branch 84.
Another liquid branch line 82 provides communication between ~ ;-the forward acting chamber 18 of the ram 11 and also the - corresponding forward acting chamber of the ram 12 (not shown in Figure ~) and control valve member 76. The reverse acting chamber 19 i5 placed in communication with the control valve ~:~ . : .
member 76 by means of the liquid line 84. Lines 82' and 84' `-, supply a twin ram (not shown) in this example but a second ,:~- . .
ram is not necessary to the functioning of the system. ~ -` 20 To prevent overloading the system of Figure 4 there is additionally provided an unloading relief valve 85 in the liquid line 75 coupled with a check valve 86 permit-ting flow through the liquid line 75 to the control valve 76.
.. ~ , There is also an exhaust liquid line 87 from the control ' val~e member 76 to the reservoir 64.
In operation, let it be assumed that forward action o~ the ram 11 and piston 13 is at 1,200 pounds per square , inch. In this event the sequence valve means 59 is set for ~, operation at 1,200 pounds per square inch. For this type of system the sequence valve means 69 will direct passage of , '', -11- ' , ~ "

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: . ~ . : : .'. , , ~ , 1~)54C~Z7 liquid under pressure pas-t a chec]c valve 90 to the control valve 71 which, by me,ans of solenoid 73 being in.direct com-munication wi-th electric power.to the pump motor 67, will a~sume thc positi.orl shown in Figure 4 and allow passage of liquid to the accummulator 60 while a~ the same t.ime prevent Elow of liqu:i.d ~nder pressure through the liquid line 75, until a p.ressure of 1,200 pounds per square inch has been : ~uilt up in the accummulator 60. When this happens, and with the control valve member 76 set in the position shown : ~
. 10 in Figure 4, by means oE electrical power at the solenoid 73 , ,- which is in direct communication with the electrical power : ~, : to the motor 67,' liquid under pressure passes through the ; liquid line'82 to the forward acting chamber 18 of the ram 11, causing the piston 13 to be moved downward a~s shown in Figure 4. Meanwh.ile, any liquid present in the reverse act- '' ing ch~lber 19 flows outwardly through the liquid line 84, through the control valve member 76 to the exhaust liquid line 87 and then bac]c to the reservoir 64. Fluid is pre-vented from flowing from the reverse acting chamber 19 to-ward the valve 71 via line 81, 81' by action o~ the check valve 88 as tne chamber 19 is exhausting. ' ' , When-reverse operation is desired, by proper manip- ~ ' '~ ula~ion of the solenoids 77 and 78, namely deenergize sole-.................................................................... ... . . . .
noid 77 and energize solenoid'78, the control valve member' '~
76 is shifted from left to right and as shown to the extreme '~ ~ :
position wherein travel of liquid through the control valve - .
member 76 is reversed. This means,that liquid under pres-' sure from the liquid line 75.is passed through the liquid - line 84 to theireverse acting chamber 19 to cause the piston 13 and piston rod 14 to move upwardly. At the same time '~

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~054t:3 ~7 exhaust is accomplished from the forward acting chamber 18 by liquid therein passing through the li.quid line 82 through the control valve member 76 and thence -through the exhaust ].iquid line 87 to the reservolr 64.
Irrespective of whether the piston is acting for-ward or in reverse, by suitable conventional electrical con~
nections, when the control valve member 76 has been set to :.
pass liquid under pressure to either one or the other of the chamber 18 or 19 of the ram 11, the control valve member 71is set to an adjustment by means of power to the solenoid 73, wherein flow from the liquid line 70 is opened and flow .
from the liquid chamber 62 and liquid line 72 is prohibited from flowing through the control valve member 71 by the check valve 90 in the liquid line 70. If however, through leakage or some other means pressure in the liquid chamber 62 falls .
below the selected pressure (1200 psi) the sequence valve 69 . will replenish chamber 62 before any more fluid can flow to the line 75 insuring the-proper pressure in the accummulator :.
~ 60, and also volume.
: 20 In this form of device operation in both forward . ~.
and reverse is done under the same 1,200 pounds per square inch condition, the pressure in the accumulator 60 being maintained from the sequènce valve 69.
. . For holding the piston 13 in any one position the .: 25 solenoid valve arrangement operates in a fashion such that ~ the control valve 76 is moved to center position by spr.ings :. 79 and 80 when solenoids 77 and 78 are both deenergized ....
wherein liquid flow from the liquid line 84 is blocked.
~ There is no movement of liquid in the liquid line 75 by rea- ~
:.`` 30 son of the shift in positiOn of the control valve member 76 . ~: :

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to the center position shown in Figure 4.
Should movement of the piston rod 1~ be blocked for any reason while ~he pump and mokor continue to operate to the extent that pressure gets built up in the system to a level siynificantly above 1,200 pounds per square inch, the unloading relief valve 85 set at a slightly higher pressure, as for example 1,500 pounds per square inch, is adapted to actuate releasing liquid at the higher pressure to pass through a llquid release line 89 and thus back to the reser-voir 64.
In the event of failure of electrical power afterthe piston 13 has been moved to the forward limit, or any portion of the forward operation, there is still the capa~
bility to automatically return the piston to initial posi-tion. With the control valve member 76 in the position or ~ .adjustment in the center as it would be when neither solenoid was energized (i.e. power failure~, with the control valve .
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: member 71 set in its left hand position as would happen when - .
the solenoid 73 had no power allowing spring 74 to move the : ~
. 20 valve, liquid under pressure from the liquid chamber 62 of : .
the accumulator 60 can flow through a line 81', past the ~ -check valve 88, through the liquid lines 81 and 84 to the return chamber 19, there having been build up prior to ini-tial operation enough li~uid pressure and volume in the accumulator 60 to complete the cycle, by means of sequence valve 69. The action described consequently moves the piston 13 upward to its original position. While piston 13 is mov- - ~
ing upward, fluid in chamber 18 flows through line 82 through ~ :
valve 76 at its center position, since with no power springs 79 and 80 move it to the center position allowing fluid to -;~ :

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, ~54CI Z7 escape through the line 87 into the reservoir 64.

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Claims (24)

The embodiments of the invention in which an ex-clusive property or privilege is claimed are defined as follows:

1. In a system for performing work by operation of a hydraulic ram having a piston therein forming in said ram a foreward chamber and a reverse chamber, said system comprising a source of fluid at fore-ward operating pressure, a fluid pressure storage container including fluid passage means connecting said container to said source, operating valve means having fluid passage means connecting said operating valve means respectively to said source, said container and said ram for selectively direct-ing fluid at said foreward operating pressure to said fore-ward chamber, said operating valve means having one adjustment wherein said foreward operating pressure is passed to said foreward chamber and said reverse chamber has a connection to exhaust, sequence valve means connected respectively to said container, said source and said operating valve means, said sequence valve means having an adjustment at pressures less than said foreward operating pressure which inhibits passage of fluid by said operating valve means to said foreward chamber until said container is at said fore-ward operating pressure, said operating valve means having another adjust-ment connecting said foreward chamber to exhaust, and a fluid connection between said container and said reverse chamber operative to reverse action of said ram when said foreward chamber is connected to exhaust,

2. A system as in Claim 1 wherein said sequence valve means includes an unloading vent operative prevent overloading said system with fluid pressure.

3. A system as in Claim 1 wherein the source of fluid pressure is air and said operating valve means prises a selector valve unit connected to said source and a pilot operated valve unit responsive to said sequence valve means when at said foreward operating pressure, said pilot operated valve unit having one position wherein passage of air from the selector valve unit is blocked and the foreward chamber is connected to exhaust and another position wherein air is passed to the foreward chamber.

4. A system as in Claim 3 wherein said fluid con-nection between the container and the reverse chamber con-tains a pressure relief valve set at a pressure less than said foreward operating pressure and a pressure regulator set at a pressure less than the setting of said pressure relief valve.

5. A system as in Claim 3 wherein the sequence valve means is connected directly to the container and there is a pilot fluid pressure line from said sequence valve means to said pilot operated valve unit.

6. A system as in Claim 3 wherein there is a constantly open restricted vent connected to said sequence valve means.

7. A system as in Claim 4 wherein the pressure regulator is set at a pressure not higher than about one fourth the foreward operating pressure.

8. A system as in Claim 1 wherein said operating valve means comprises a selector valve unit connected to said source, a pilot operated valve means responsive to said sequence valve means when at said foreward operating pressure, said pilot operated valve means having one position wherein passage of air from the sequence valve means is blocked and another position wherein air is passed to the foreward chamber, an air line from the pilot operated valve means to said foreward chamber and a quick exhaust valve unit in said air line.

9. A system as in Claim 1 wherein said container has a gas chamber, a liquid chamber and a movable separator therebetween, the liquid chamber being in communication with the fluid passage means which is connected to said source.

10. A system as in Claim 9 wherein said source of fluid comprises a liquid reservoir and a power operated pump.

11. A system as in Claim 10 wherein there is an unloading relief valve connected respectively to said se-quence valve means and said operating valve means having a pressure setting in excess of said foreward operating pres-sure and a discharge from said relief valve to said reser-voir.

12. A system as in Claim 9 wherein said operating valve means comprises two valve members, one of said mem-bers having one adjustment wherein the liquid reservoir is connected to said sequence valve means and disconnected from said ram and another adjustment wherein the liquid chamber is disconnected from said sequence valve means and connected to said ram.

13. A system as in Claim 9 wherein said operating valve means comprises two valve members, a second of said valve members having a first adjustment wherein said sequence valve means is connected to a first of said ram chambers and a second of said ram chambers is connected to exhaust and a second adjustment wherein said second of said ram chambers is connected to said sequence valve means and said first of said ram chambers is connected to exhaust.

14. A system as in Claim 13 wherein said second of said valve members has a third position wherein the fluid passage means from said sequence valve means to said operat-ing valve means is blocked.

15. A system as in Claim 9 wherein said operating valve means comprises two valve members, one of said valve members having one adjustment wherein the liquid reservoir is connected to said sequence valve means and disconnected from said ram and another adjustment wherein the liquid chamber is disconnected from said sequence valve means, the other of said valve members having a first adjustment where-in said sequence valve means is connected to the first of said ram chambers and a second of said ram chambers is con-nected to exhaust, and a second adjustment wherein said second of said ram chambers is connected to said sequence valve means and said first of said ram chambers is connected to exhaust.

16. In a system for performing work by operation of a gas actuated ram comprising a cylinder and a piston therein forming in said cylinder a forward chamber and a reverse chamber wherein said reverse chamber has a re-verse exhaust means at a pressure exceeding ambient pres-sure, and wherein said piston is movable between full forward and reverse positions, said system comprising a source of gas at forward operating pressure, a gas storage container means of capacity at least equal to the capacity of the reverse chamber with the piston at said full reverse position, said container means including gas passage means connecting said container means to said source, operating valve means comprising a forward acting member and a for-ward exhaust member, said forward acting member including gas passage means interconnecting said source, said con-tainer means and said forward chamber, said operating valve means having one adjustment wherein said forward acting member is in a position wherein said source is connected to said forward chamber for passing gas at forward operating pressure to said forward chamber and wherein said reverse chamber has a connection to said reverse exhaust means, sequence valve means interconnected with said container means and said operating valve means, said sequence valve means having a first automatic adjust-ment at pressures less than said forward operating pres-sure operative to inhibit passage of gas by said operating valve means to said forward chamber, said sequence valve means having a second automatic adjustment when said con-tainer means is at said forward operating pressure, said operating valve means having another adjustment in response to said second automatic adjustment of the sequence valve means wherein said forward exhaust member connects said forward chamber to exhaust and said source is disconnected from said forward chamber, a gas connection between said container means and said reverse chamber, said last con-nection being operative to pass gas under pressure to said reverse chamber whereby to reverse action of said ram when said forward chamber is connected to exhaust.

17. A system as in claim 16 wherein said sequence valve means includes an unloading vent operative to prevent overloading said system with fluid pressure.

18. A system as in claim 16 wherein the source of gas pressure is air and said operating valve means comprises a selector valve unit connected to said source and a pilot operated valve unit responsive to said sequence valve means when at said forward operating pressure, said pilot oper-ated valve unit having one position wherein passage of air from the selector valve unit is blocked and the forward chamber is connected to exhaust and another position wherein air is passed to the forward chamber.

19. A system as in claim 18 wherein said gas connec-tion between the container and the reverse chamber contains a pressure relief valve set at a pressure less than said forward operating pressure and a pressure regulator set at a pressure less than the setting of said pressure relief valve.

20. A system as in claim 18 wherein the sequence valve means is connected directly to the container and there is a pilot gas pressure line from said sequence valve means to said pilot operated valve unit.

21. A system as in claim 18 wherein there is a con-stantly open restricted vent connected to said sequence valve means.

22. A system as in claim 19 wherein -the pressure regulator is set at a pressure substantially less than the forward operating pressure.

23. A system as in claim 16 wherein said operating valve means comprises a selector valve unit connected to said source, a pilot operated valve means responsive to said sequence valve means when at said forward operating pressure, said pilot operated valve means having one position wherein passage of gas from the sequence valve means is blocked and another position wherein gas is passed to the forward chamber, a gas line from the pilot operated valve means to said forward chamber and a quick exhaust valve unit in said gas line.

24. A system as in claim 16 wherein said last con-nection is constantly open and the pressure between said last connection and said reverse chamber is less than the pressure at said source.