WO1995032080A1

WO1995032080A1 - Improved hand tools

Info

Publication number: WO1995032080A1
Application number: PCT/AU1995/000302
Authority: WO
Inventors: Noel Albert Ross
Original assignee: Noel Albert Ross
Priority date: 1994-05-24
Filing date: 1995-05-24
Publication date: 1995-11-30
Also published as: AU6331094A

Abstract

A tool of the type having an active member (20) adapted for movement from a rest position to an operative position to perform a selected action and actuating means (11) associated with the active member (20) and including a driven member (23) co-acting with the active member (20). The driven member (23) is operable to displace the active member (20) to the operative position and the actuating means (11) includes wedge means (25) and driving means (50, 51, 52) for reciprocating the wedge means (25). Preferably the driving means (50, 51, 52) comprises a fluid operated actuator, such as a hydraulic actuator and preferably, an electrically operated hydraulic pump is incorporated into the tool. Preferably, the tool is a hand tool (10) having a pair of jaws (20) at least one of which is moveable to or from the other and actuating means (11) for actuating the or each moveable jaw (20), the actuating means (11) including a follower (23) associated with the or each jaw (20) and a fluid operated ram (50, 51, 52) adapted to displace the or each follower (23) laterally of the ram axis so as to move at least one jaw (20) to the other. Preferably the follower (23) cooperates with the ram (50, 51, 52) in such manner that it may be retracted from an actuated position by reverse operation of the ram.

Description

"IMPROVED HAND TOOLS This invention relates to improved tools and to fluid operated actuation means suitable for such tools.

For illustrative purposes this invention will be described with reference to its application to hand held pneumatically operated bolt and rod cutters but it is to be understood that this is given by way of illustrative example only and that the present invention may be applied to other forms of tools including hand or robot operated tools which utilise a shearing or clamping action such as swaging tools, crimping tools, rod and pipe benders, cable cutters, tyre bead breaker devices, grabbing and grappling devices and cutting devices such as for cutting limbs from trees or horns from cattle. Pneumatically operated hand tools such as bolt cutters have been provided in the past. However such cutters are relatively inefficient in that they utilise conventional toggle mechanisms of manually operated devices for gaining mechanical advantage between the pneumatic actuator and the jaws. Such toggle mechanisms are designed particularly for manual clamping of the jaws where only small actuating forces are available and are relatively complex and inefficient for use in pneumatically operated devices.

Furthermore in prior art pneumatically operated devices, desired increases in applied clamping or cutting forces are achieved by either increasing the operating pressure of the pneumatic actuator or by increasing the piston and cylinder diameter of the pneumatic actuator. As a result physical constraints and manufacturing costs effectively limit the force which may be applied in currently available pneumatically actuated tools.

The present invention aims to alleviate one or more of the above disadvantages and to provide improved tools and fluid operated actuation means suitable for such tools which will be reliable and efficient in use. With the foregoing in view, this invention in one aspect resides broadly in a tool of the type having a active member adapted for movement from a rest position to an operative position to perform a selected action and actuating means associated with said active member and including a driven member co-acting with said active member and operable to displace said active member to said operative position, characterised in that said actuating means includes wedge means and driving means for reciprocating said wedge means. The driving means may comprise means for reciprocating the driven member and may be in the form of a linear actuator associated with a wedge shaped driven member. The linear actuator may be in the form of an electrically driven threaded shaft associated with a take-off nut mounted on the wedge member.

If desired, the actuating means may be a manual ratchet mechanism or the like. Alternatively the driving means may be a cam or an eccentric adapted from manual or solenoid operation for example. Preferably however the driving means comprises a fluid operated actuator, such as a pneumatic or hydraulic actuator. Where a hydraulic actuator is utilised, an electrically hydraulic pump may be incorporated into the tool.

In a further aspect this invention resides broadly in a hand tool having a pair of jaws at least one of which may move to or from the other and actuating means for actuating the or each said moveable jaw, said actuating means including a follower associated with the or each said jaw and a fluid operated ram adapted to displace the or each said follower laterally of the ram axis so as to move said at least one said jaw to the other.

Preferably the follower cooperates with the ram in such manner that it may be retracted from an actuated position by reverse operation of the ram. Each jaw member may have a follower associated therewith, and of course if desired more than one follower may be associated with each jaw member and adapted to cooperate with the driven member during different phases of operation thereof. One jaw member may be fixed and the other jaw member may move towards and away from the fixed jaw member.

Alternatively, both jaw members may move relative to each other. For this purpose the jaw members may be supported on linkage mechanisms for parallel or substantially parallel movement towards one another or they may be pivotally connected together for pivotal movement between the operative and inoperative attitude.

In a preferred embodiment of the invention the jaw members are linked to one another by a pivotal connection and each jaw member supports a follower adapted to engage with respective opposite faces of a reciprocable wedge member. It is also preferred in such embodiment that the opposed faces of the wedge members are substantially linear have respective complementary faces arranged in spaced relationship therewith and engageable with the respective follower whereby retraction of the wedge member will move the jaw members apart. It will be appreciated that non¬ linear faces to the wedge may be provided in order to provide a variable mechanical advantage with respect to the position of the wedge shaped member. In a further aspect this invention resides broadly in fluid operated actuating means including a telescopic cylinder assembly having handle means associated with the cylinder, fluid supply control means associated with said handle means and tool mounting means associated with the end of the cylinder from which the telescopic shaft protrudes. Preferably the handle is associated with the end of the cylinder remote from the tool mounting means but of course it could be associated with a respective one or both opposite sides of the cylinder. It is also preferred that the fluid supply control means be controlled by a gripping action associated with the handle means.

It is preferred that the cylinder assembly be so formed and arranged that a plurality of cylinders may be coaxially mounted and mechanically interconnected and that the fluid supply control means provides a fluid supply to each of the cylinders. For this purpose each telescopic cylinder assembly may be provided with releasable mounting means whereby the telescopic shaft may be connected to or operatively associated with the telescopic shaft on the adjacent cylinder and intermediate telescopic cylinder assemblies may be provided with further mounting means enabling further telescopic cylinder assemblies to be connected thereto.

Alternatively the cylinder assembly may be in the form of an elongate cylinder having retention means therein whereby an intermediate reaction plate or plates may be arranged in longitudinally spaced relationship within the cylinder such that a plurality of pistons may be supported on a telescopic shaft which passes sealably through the reaction plate or plates enabling output effort multiplication by the interconnection of additional pistons and associated reaction plates within the cylinder assembly.

In a further alternative, the cylinder may be circular in section and include several ports disposed about a circular bore. Two or more galleries may be provided coaxial with the bore of the cylinder, and where a relatively large number of galleries are provided, some of such galleries may be used for alternative purposes. For example, one or more may be allocated for pneumatic fluid such as air, or hydraulic fluid such as oil, or as conduit for control and/or signal cables.

In yet a further aspect, this invention resides broadly in a method enabling output effort multiplication from a fluid actuated ram assembly having a cylinder assembly, a piston within the cylinder assembly and supported on a ram shaft extending from one end of the cylinder assembly, the method including:- inserting cylinder division means within the cylinder intermediate said piston and said one end and through which said ram shaft may pass in sealed relationship; attaching a further piston to said shaft intermediate said cylinder division means and said one end, and directing fluid supply simultaneously to common sides of said piston and said further piston. In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate typical embodiments of the present invention and wherein:

FIG. 1 is a perspective view of a rod or bolt cutter according to the present invention;

FIG. 2 is an end view illustrating the jaws of the cutter in the open position;

FIG. 3 is a sectional view of a multi piston embodiment of the invention; FIG. 4 is a sectional view along the line 4-4 of FIG. 3;

FIG. 5 is a sectional view corresponding to FIG. 3 and illustrating the air supply galleries;

FIG. 6 is a sectional view along the line 6-6 of FIG. 5;

FIG. 7 (shown collectively as figs 7(1) and 7(2)) illustrates a further embodiment of the invention;

FIGS. 8 and 9 (shown collectively as figs 9(1) and 9(2) illustrate alternative forms of a cylinder casing for the invention;

FIGS. 10 and 11 illustrate an alternative embodiment of the invention utilising hydraulic fluid;

FIGS. 12 and 13 illustrate a further embodiment of the invention having a hollow piston;

FIGS. 14 and 15 illustrate a further embodiment of the invention having a remote actuation of the jaws; FIG. 16 illustrates an alternative embodiment of the invention utilising a hydraulic pump; FIG. 17 illustrates an alternative porting arrangement for a tool with a hollow piston, and FIG. 18 illustrates the external features of an alternative form of the invention to that shown in FIG. 1.

Referring initially to FIGS. 1 and 2 it will be seen that the bolt or rod cutter 10 has a pneumatic ram assembly 11 provided with a supporting handle 12 at one end and the cutting head assembly 13 at the opposite end. A transition housing 14 extends between the cutting head assembly 13 and the ram assembly 11. The supporting handle 12 has an associated trigger 15 connected thereto and adapted to actuate a two-way valve 16 provided with an air inlet connection 17 for connecting the cutter 10 to an air supply hose.

The cutter 10 is operatively identical to the cutter 10a illustrated in FIGS. 3 to 6. However whereas the latter embodiment utilizes two actuating pistons the cutter 10 utilizes a single actuating piston and thus its ram assembly 11 is relatively short. In addition the cutting force which may be applied by the cutter 10 is approximately one half that which may be exerted by the cutter 10a. However in both embodiments the cutter head assembly 13 and the transition housing 14 are identical. As shown the cutting head assembly 13 includes a pair of jaws 20 pivotally connected at 18 to a mounting 21 supported at the front of the housing 14. The jaws 20 are gear connected at 19 for simultaneous operation and each extends rearwardly at 24 internally of the housing 14 to support a pair of rotary follower assemblies 23. The inside faces of the rearwardly extending jaw portions 24 diverge rearwardly when the jaws 20 are closed so as to enable a correspondingly shaped wedge member 25 which is connected to the telescopic ram shaft 26 to be accommodated therebetween. The wedge member 25 may be moved between the followers 23 by the ram assembly 11a to close the jaws. The wedge member 25 is formed integrally with an external shroud 26 provided with flanges 27 arranged parallel to the wedge faces such that upon retraction of the ram assembly 11 the flanges 27 engage the rotary followers 23 and move them towards one another with a resultant opening of the jaws 20.

The trigger 15 is guided for movement to and from the handle 12 and includes a cam portion 28 which extends forwardly to engage with the control member 29 of the tow- way valve 16 such that retraction of the trigger 15 towards the handle 12 depresses the control member 29 and actuates the valve 16 to cause extension of the ram assembly 11 and thus actuation of the jaws 20. Release of the trigger causes retraction of the ram assembly 11 and thus opening of the jaws 20.

The ram assembly 11a includes a cylinder 31 having a plain bore 32 in which pistons 33 and 34 engage. A circlip groove 35 is provided in the bore 32 for retention of an intermediate reaction plate 36 provided with seals for sealably engaging the cylinder 31 and the ram shaft 41 which passes slidably therethrough. The cylinder 31 is suitably formed of a relatively lightweight material such as aluminium whereby it may be extruded with integral cylinder galleries 37, the ends of which are internally threaded to enable end plates 38 and 39 to be secured thereto. The cylinder galleries 37 communicate with transfer galleries formed in the end plates 38 and 39 and the reaction plate 36 which is retained in the cylinder 31 by a circlip 40. As illustrated in FIG. 5, the end plate 38 includes transfer galleries which communicates with the air inlet 17, the two-way valve 16, the cylinder 31 and the cylinder galleries 37 whereby the two-way valve 16 may be operated to selectively supply fluid for closing or opening of the jaws 20. The reaction plate 36 includes transfer galleries which communicate with the cylinder 31 and the cylinder galleries 37, and the end plate 39 includes transfer galleries which communicate with the cylinder 31 and the cylinder galleries 37. Communication between the cylinder galleries 37 and the end plates 38 and 39 is through the hollow ported bolts 42, as illustrated.

One of the galleries [not shown] exhausts into the cutting head assembly 13 through the port 43 via the bolt 42 so as to supply a lubricating mist associated with the air supply thereto. The exhaust air is supplied through the two-way valve 16. Another gallery 37a connects the valve 16 with the reaction plate 36 through the port 45 and through the port 46 and the bolt 42. The end plate 38 connects with the valve 16 through port 46 to simultaneously supply air for delivery to the cylinder 31 to extend pistons 50 and 51 and the supporting ram shaft 52. Another gallery 37b connects the two-way valve 16 with the reaction plate 36 through a port 53 and the end plate 39 through a port 54 via bolt 42 to simultaneously supply air for delivery to the cylinder 31 to retract pistons 50 and 51 and the supporting ram shaft 52.

Thus the single control valve 16 may be utilised to extend the ram shaft 52 or retract it as desired. The ram shaft 52 is connected to the wedge member 25 whereby extension and retraction of the shaft causes closing and opening of the jaws 20. The arrangement is such that the two-way valve 16 normally provides a fluid connection between the inlet 17 and the gallery 37b so that the pistons 51 and 52 are held in the retracted attitude. When the trigger is depressed air is diverted to the gallery 37a to extend the ram and close the jaws 20 through interaction of the wedge member 25 with the followers 23. Immediately upon releasing the trigger 15 air supply is diverted to the front of the piston and the wedge member 25 is retracted. To ensure that the jaws 20 are opened after each cutting operation, the trigger is spring biased away from the handle 12.

The ram assembly 11 may be utilised for actuating devices other than the cutting head assembly 13 as desired. In instances where a relatively high actuating force is required together with a relatively small stroke the actuating force can be increased by adding further pistons on the ram shaft and further reaction plates intermediate the adjacent pistons, and any desired stroke may be provided by selecting a suitable length cylinder. According to the present invention where the cylinder is an extrusion, rams with desired strokes and actuating forces may be readily provided utilizing common components. Furthermore, if desired, the ram assembly could actuate rockers or pivot cams to force apart the trailing ends of the jaws and thus move them to a closed position.

In the embodiment illustrated in FIG. 7 the ram assembly 60 is extended by interposing a further barrel 61 and reaction plate 62 between the ram 60 and the end plate 63. As in the previous embodiment, an external air supply connection is taken from a gallery 64 to the reaction plate 62 to supply air to the front of the ram assembly 60.

A piston rod 65 abuts the piston 68 which is supplied with air on its downstream face as per the previous embodiment to open the jaws 20 upon release of the trigger 15. External porting and piping could be used if desired to provide the necessary connections between the valve and the pistons. Additionally separate valves could be used to control closing and opening of the air supply passages and the valves could be mounted remote from the handle or associated with a further handle at the side of the ram assembly.

Referring to FIG. 8, an alternative cylinder 81 includes four integral galleries 87, the ends of which are internally threaded in a similar fashion to that of the cylinder 31 for receiving respectively four hollow bolts shown typically at 85. The galleries 87 communicate with transfer galleries formed in a reaction plate 89. An end plate 84 is penetrated by a ram shaft 86. Two abaxial transfer galleries in the reaction plate receive 89 air for actuating or retracting the tool, and an axial gallery receives exhaust air. At appropriate locations along the length of the alternative cylinder, one or more of the galleries are in fluid communication with the internal space of the cylinder to permit operation of the tool. Referring to FIG. 9, an circular cylinder 91 includes eight integral galleries 97 which communicate with transfer galleries formed in a reaction plate 99. An end plate 94 is penetrated by a ram shaft 96. An actuation transfer gallery 94 or a retraction gallery 93 in the reaction plate 99 receives air for actuating or retracting the ram shaft 96 respectively and an exhaust 95 gallery receives exhaust air. In the embodiment shown in FIGS. 10 and 11, a hydraulic tool 100 is shown in the retracted position in FIG. 11 and in the actuated position in FIG. 10. The hydraulic tool 100 includes a main cylinder 101 having a pneumatic end 102 and a hydraulic end 103.

The distal portion of the hydraulic end 103 includes an actuated assembly 104 and the distal end of the pneumatic end 102 includes an end plate 105. A valve 106 may be actuated to supply air from an air supply 107 through respective ports.

The supply air is generally shown by the reference numeral 115. Once the air has been used to actuate or retract the actuated assembly 104, it is exhausted through exhaust ports generally through the actuated assembly 104 such that any lubrication missed may be provided by the actuated assembly 104. The exhaust air generally indicated by the numeral 116. Supply air 115 or exhaust air 116 is supplied to the actuated assembly 104 through an air bypass 117. The air supply 117 is used to actuated the assembly by operative actuation of a pneumatic ram assembly 108.

The pneumatic ram assembly 108 is moved actually with respect to the main cylinder 101 by the introduction of the supply air 115 to a first actuation plenum 110 and a second actuation plenum 113. When the valve 106 is released, the supply air 115 is directed into a first retraction plenum 111 and a second retraction plenum 112.

The portion of the pneumatic ram assembly 108 remote from the valve 106 constitutes a hydraulic ram 109. Actuation of the valve 106 causes the hydraulic ram 109 to be moved actually into a hydraulic retraction plenum 125 which forces hydraulic fluid through an actuation non-return valve 122 into a hydraulic actuation plenum 124.

In the embodiment shown, several actuations and retractions of the pneumatic ram assembly 108 and correspondingly the hydraulic ram 109 may be used progressively fill the hydraulic actuation plenum 124 with hydraulic fluid to move an operating shaft 114 so as to actuate the actuated assembly 104. Alternatively, the dimensions of the hydraulic retraction plenum 125 and hydraulic actuation plenum 124 and/or the dimensions of the hydraulic ram 109 may be such that a single actuation of the pneumatic ram assembly 108 is sufficient to operate the actuated assembly 104. In order to cause the actuated assembly 104 to retract, a bleed valve 123 is opened to permit hydraulic fluid to escape from the hydraulic actuation plenum 124 into a reservoir 128.

An annular reservoir piston 129 is movable axially with respect to the main cylinder 101 according to the amount of hydraulic fluid in the reservoir 128. A hydraulic take-up spring 120 is provided to provide a biasing force to urge the reservoir piston 129 towards a dividing wall 118 which divides the pneumatic end 102 from the hydraulic end 103. Hydraulic oil returns to the reservoir 128 through a hydraulic return line 126.

Additionally, a return spring 121 urges the hydraulic ram 109 to the retracted position as shown in FIG. 10 when the bleed valve 123 is opened. When the hydraulic ram 109 is retracted, hydraulic fluid is replenished in the hydraulic retraction plenum from the reservoir 128 through a reservoir non-return valve 127.

Referring to FIGS. 12 and 13, a hydraulic tool 130 includes a main cylinder 131 supplied with the air supply 107 in a similar fashion to that shown in FIGS. 10 and 11. The particular arrangement shown indicates the porting and valving arrangements for a main cylinder which does not have fluid transport galleries along its peripheral edge. This is achieved by providing a hollow piston assembly 132 shown in the actuated position in FIG. 12 and the retracted position FIG. 13.

When the air supply 107 is directed through the tool 130 with the valve 106 depressed, the supply air 115 is directed into a first actuated plenum 110 and a second actuated plenum 113.

When the valve 106 is released, supply air 115 is directed to a first retraction plenum 111 and a second retraction plenum 112.

The exhaust air 116 is directed in each case through the hollow axis of the hollow piston assembly 132. Motion of the hollow piston assembly 132 through the main cylinder 131 causes a first port 133 to move from the first actuated plenum 110 to the first retraction plenum 111. A second port 134 correspondingly receives air into the hollow piston assembly 132 from the second retraction plenum 112 during actuation and directs air to the second retraction plenum 112 during retraction of the hollow piston assembly 132. A third port 135 provides for exhaustion of exhaust air 116 to the extent that it is not exhausted through the actuated assembly 104. Referring to FIGS. 14 and 15, an actuation mechanism 140 is provided with pneumatic and/or hydraulic actuation as herein described and maybe actuated from a retracted position shown in FIG. 14 to an actuated position shown in FIG. 15 by a trigger assembly 141. An actuated head assembly 142 is provided remote from the actuation mechanism 140 by a rigid or flexible connecting conduit 143 through which a rigid or flexible actuation member 144 is movable axially. Referring to FIG. 16, an electrohydraulic tool 150 includes a hydraulic pump 155 and valve assembly 156 contained within a main cylinder 151. A switch assembly 152 is actuated by a trigger switch 154 for activating the hydraulic pump 155. Hydraulic oil is forced through the valve assembly 156 to move a hydraulic ram 159 in direction of an arrow 160 to actuate the actuated assembly 104. Hydraulic oil is provided from a reservoir 157 divided from the hydraulic ram by a dividing cylinder 158. Respective springs are used to cause the hydraulic ram 159 to retract and permit the reservoir 157 to be filled and emptied with hydraulic oil.

Referring to FIG. 17, an alternative porting arrangement is shown for a hollow ram tool 170, which includes a hollow ram 172 for increased strength per unit mass. A tube 169 is sealable by a seal 171 and slidable inside the hollow ram 172. The tube 169 is affixed at one end into an end plate 178 and aligned with the exhaust gallery 177 of a two-way valve 166 to exhaust directly to the end of the hollow ram 172 into an assembly via gallery ports in the ram shaft 172 and wedge member (not shown).

A generous tolerance in fitment of the cutter jaws permits exhaust air to escape without undue restriction and at a reduced velocity to minimize noise and blow dust and debris from material being cut away from the cutting head assembly to increase the working life of the cutting head components.

Alternatively, the hollow ram 172 may include an extra internal tube to feed fluid internally to the piston chambers through port apertures in the main hollow ram 172 and seals between each tube which allows fluid to be directed without contamination within the assembly. Additionally a damper on resilient material may be provided to reduce shock loading when the hollow ram 172 come to the end of its stroke. The embodiment shown in FIG. 18 illustrates the external features of an alternative form of the invention to that shown in FIG. 1. An alternative housing 180 includes a safety guard 181, which is constituted by a tubular sleeve slidable over the cutting head housing 188 open at both ends and protruding beyond and over the cutting jaws 189. A notch 182 in line with the entrance to the cutting jaws 189 may be used to locate the tool onto bar material to be cut and/or assist in alignment of the tool.

A bracket 183 is attached to the safety guard 181 to operate against a spring urged push rod 184 to prevent supply air being accidentally applied unless the safety guard 181 is in a retracted position. The push rod 184 may me passed through one of the galleries of the cylinder not being used to supply fluid to operate the tool. In the embodiment shown, the push rod 184 passes through to the handle and ends at the reference numeral 185 near a trigger 187 to prevent the trigger being operated.

The safety guard may also be manipulated by hand to permit, for example, the operator visual access to the cutting operation.

It will of course be realised that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as is herein set forth.

Claims

THE CLAIMS DEFINING THIS INVENTION ARE AS FOLLOWS:-

1. A tool of the type having a active member adapted for movement to and from an operative position to perform a selected action and actuating means associated with said active member and including a driven member co-acting with said active member and operable to displace said active member to said operative position and said actuating means includes wedge means and driving means for reciprocating said wedge means.

2. A tool as claimed in claim 1, wherein said wedge means includes a ramp face which co-operates with a follower associated with said active member and wherein there is provided restraining means on said wedge means which restrains said follower for movement adjacent said ramp face.

3. A tool as claimed in claim 2, wherein said restraining means includes a complementary face arranged in spaced relationship with said ramp face.

4. A tool as claimed in claim 2 or 3, wherein said follower is a rotary follower supported for rotation on said active member and about an axis parallel to the respective ramp face.

5. A tool as claimed in any one of claims 1 to 6, wherein said driving means is a pneumatic ram.

6. A tool as claimed in claim any one of the preceding claims, wherein said active member constitutes one of a pair of opposed jaws or blades each adapted for movement to and from a mating operative position and wherein said driven member co-acts with both said active members.

7. Fluid operated actuating means including a telescopic cylinder assembly having handle means associated with the cylinder, fluid supply control means associated with said handle means and tool mounting means associated with the end of the cylinder from which the telescopic shaft protrudes.

8. Fluid operated actuating means as claimed in claim 7, wherein said handle is associated with the end of the cylinder remote from the tool mounting means and said fluid supply control means is controlled by a gripping action associated with said handle means.

9. A hand tool having a pair of jaws at least one of which may move to or from the other and actuating means for actuating the or each said moveable jaw, said actuating means including a follower associated with the or each said jaw and a fluid operated ram adapted to displace the or each said follower laterally from the ram axis so as to move said at least one said jaw to the other.

10. A hand tool as claimed in claim 9, wherein said actuating means includes wedge means associated with said fluid operated ram and engageable between respective followers supported on said jaws.

11. A hand tool as claimed in claim 9, wherein said wedge means includes opposed ramp faces and restraining means which restrain said followers for movement adjacent respective said ramp faces.

12. A method enabling output effort multiplication from a fluid actuated ram assembly having a cylinder assembly, a piston within the cylinder assembly and supported on a ram shaft extending from one end of the cylinder assembly, the method including:- inserting cylinder division means within said cylinder assembly intermediate said piston and said one end and through which said ram shaft may pass in sealed relationship; attaching a further piston to said shaft intermediate said cylinder division means and said one end, and directing fluid supply simultaneously to common sides of said piston and said further piston.