CN1182004A

CN1182004A - Pneumatic actuator device

Info

Publication number: CN1182004A
Application number: CN97110831A
Authority: CN
Inventors: 埃里克·肖弗托; 里夏尔·谢纳
Original assignee: Etablissements Caillau SAS
Current assignee: Caillau SAS
Priority date: 1996-05-03
Filing date: 1997-04-30
Publication date: 1998-05-20
Also published as: MX9703307A; ZA973812B; NO972053L; HU9700825D0; PL319779A1; DE69702683T2; CZ135197A3; EP0805278B1; HUP9700825A3; NO972053D0; HUP9700825A2; JPH1037911A; DE69702683D1; TW343168B; ATE195162T1; FR2748298A1; KR100227523B1; AR006938A1; CA2204077A1; FR2748298B1

Abstract

A pneumatic actuator device comprises the first and second pistons (18,20) movable in the first and second house (12,14) and an advance member (40). The separation wall (28) has a transverse bore (72) in which the slide of the valve is received, a first, second and third duct (74,76; 66,68; 84) which connects the transverse bore to a pressurized fluid feed (66, 68), the second axial chamber (14) or the first axial chamber (12) are in connecting each other. The slide of the valve are selectatively connecting or isolating to these ducts in the respective position.

Description

Pneumatic actuator device

The present invention relates to pneumatic actuator means, comprise an actuator body, pressure fluid is infeeded the device of the inside of described main body, the first piston that can move in first axial chamber of the rear end that is arranged in actuator body, be arranged in second piston of second axial chamber of the described first axial chamber front with at least one, device also comprises a next door that this two axial chamber is separated, with the connecting rod that piston is connected together and be suitable in described hole, sliding in the mode of sealing, described bar has a hole, its at first opening in first axial chamber behind first piston, in second axial chamber of after-opening behind second piston, piston is connected with the part of sending to that is positioned at the actuator body front, the device that infeeds pressure fluid comprises a guiding valve, it is controlled between the primary importance and the second place by control device and moves, primary importance fluid directive in described chamber at least one axial chamber behind the piston so that roof pressure is sent part to forward, and at second place fluid directive at least one axial chamber of the front of the piston of described chamber so that roof pressure is sent part to backward.

A kind of device of this class is known from the Swiss Patent No.570242 that has criticized.As an example, by with the fixture acting in conjunction of suitable shape, send part to and can be used to part punching or punching metal parts and so on.Known from US3410180 in addition, device can be with a sphenocephaly, and when sending to, it engages with jaw, pushes away them along closing direction, and when returning, allows jaw to open.In this case, device can be used for tightening up retaining ring and so on.

Thereby under fluid drives, send part to directly to sinciput or to pusher.

Widely used this class device must be with alap cost manufacturing.Therefore require the loop (being generally the compressed air loop) of fluid simple as far as possible, do not need to make the very long pipeline of accurate dimension.Also just note, when requiring this device is used for clamping retaining ring, must in very little space, operate, especially as in the engine room of vehicle.

The fluid circuit of Swiss Patent 570 242 is quite complicated.It is included in a compressed air feed conduit of actuator body back, three parallel grooves towards the big distance of front ratio of elongation, have can be in the hole during the valve seat of taper is arranged two valves of mobilizable slide block, and have can be in axial hole the 3rd valve of movable slide block.The number of this part and the compactness and the low cost that are provided with and install are inconsistent.In order to be held in treating apparatus under the situation in user's hand in actuator body, control device must extend into the middle part of actuator body.In order to make this require with the pressure fluid feed conduit and to be positioned at the guiding valve of actuator body back compatible, very long and bulky bar constitutes Swiss Patent 570242 described control device by one.Know very that from the manufacturing cost speech this is a shortcoming.The area that should note control piece is big more, and it is big more that they operate untimely danger.

The objective of the invention is to improve the actuator devices of prior art, an actuator devices that can address the aforementioned drawbacks is provided.

According to the invention provides a kind of pneumatic actuator means, comprise an actuator body, pressure fluid is infeeded the device of the inside of described main body, the first piston that can move in first axial chamber of the rear end that is arranged in actuator body, be arranged in second piston of second axial chamber of the described first axial chamber front with at least one, device also comprises a next door that this two axial chamber is separated, with piston is connected together and be suitable for the sealing the connecting rod of mode in described hole, described bar has a hole, its at first opening in first axial chamber behind first piston, in second axial chamber of after-opening behind second piston, piston is connected with the part of sending to that is positioned at the actuator body front, the device that infeeds pressure fluid comprises a guiding valve, it is controlled between the primary importance and the second place by control device and moves, primary importance fluid directive in described chamber at least one axial chamber behind the piston so that roof pressure is sent part to forward, and at second place fluid directive at least one axial chamber of the front of the piston of described chamber so that roof pressure is sent part to backward, it is characterized in that described next door has a transverse holes, the slide block of guiding valve is received within wherein, first pipeline that described transverse holes and pressure fluid feed conduit are coupled together, second pipeline that transverse holes and aft section in second axial chamber of the second piston back are coupled together, with second pipeline that transverse holes and previous section in first axial chamber of first piston front are coupled together, when the slide block of guiding valve during in primary importance, first and second pipelines are interconnected, and separate with the 3rd pipeline, when slide block is in the second place, the first and the 3rd pipeline is interconnected, and separates with second pipeline.

Should understand because the present invention, can therefore reduce the length of pipeline significantly, in addition with machining pipeline in the very simple mode next door, this set also may use the single guiding valve that is placed in the single hole, several fluid lines at position spaced opening suitably in this hole.Therefore, easier device the control slide block is also placed in middle region, therefore can reduce the length of device.

Best, the device of described control guiding valve comprises a control lever of horizontally set, the zone of the first end next door of described bar is connected with actuator body, and is installed to the pivot around the axis that extends vertically, and second end of bar is fit to cooperate with the free end of the slide block of guiding valve.

In this case, bar (measuring vertically) is quite short, because it is located immediately at the zone in next door.Bar is suitable for having the effect that makes lever arm that the enough length of easy operating can be arranged around a fact that pivots with respect to the axially extended stingy axle of actuator devices main body substantially along horizontal expansion.In addition, by making the shape of device tool compactness, reduced the non-danger of in time catching and working and improved security.

By below reading to the detailed description of the embodiment of limiting examples, can more clearly understand the present invention and advantage thereof.

The present invention will be described with reference to the accompanying drawings, in the accompanying drawing:

Fig. 1 is the axial section of apparatus of the present invention, illustrates to send part to and be in position after leaning on;

Fig. 2 is the profile that the II-II line along Fig. 1 dissects;

Fig. 3 is the top view of Fig. 1;

Fig. 4 is the view of similar Fig. 1, illustrates to send part to and be in forward position;

Fig. 5 is the part sectioned view that cuts off along V-V line among Fig. 1; With

Fig. 6 is the view of similar Fig. 5, is the part sectioned view that dissects along VI-VI line among Fig. 4.

Fig. 1-4 illustrates a pneumatic actuator, comprises an actuator body 10.Be provided with one first axial chamber 12 in the rear end of actuator body 10, and be provided with one second axial chamber 14 in the front of first axial chamber 12.In addition, one the 3rd axial chamber 16 is arranged in the front of second axial chamber 14.

First, second and

third piston

18,20,22 is located in first, second and third axial chamber respectively and activity therein.These pistons link up with a bar mutually.More specifically, bar comprises the first connecting rod 24 that connects first and

second piston

18,20, with second or " another " connecting rod 26 of being connected second and third piston 20,22.

Axial chamber

12,14 is separated by next door 28, and next door 28 has an axial hole 30, and first connecting rod 24 slides therein.In order to seal this slip, a sealing ring 32 is located in the groove in described hole, and cooperates with the excircle of bar 24.

Similarly, opened the chamber in 14,16 minutes in another next door 34.This next door 34 also has an axial hole 36, the second slide bars 26 to slide therein.Be located at sealing ring 38 these slips of sealing in the groove in hole 36.

Piston is connected with the part 40 of sending to that is located at the actuator body front.More specifically, send the front that part is fixed on the bar that connects piston to, just shown in example in be fixed on the front end 42 of second connecting rod 26.This end of sending part to is provided with screw thread 44, the threads engaged on it and bar 26 ends 42.

Shown in example in, the front end 40a that sends part 40 to is a wedge shape, just front end is fined away.

A plurality of supporting arms 46 are located at the front of actuator body.These arms 46 are fixed to the front of actuator body by retainer ring 48, and retainer ring 48 is provided with the threaded engagement of the front end of screw thread and actuator body 10.These arms 46 have support plate 50 spaced apart from each other.Two jig arm 52 are installed between support plate.The front end of jig arm is configured as the formation jaw.Wheel 52b is equipped with in their rear end, can cooperate with the part of sending to of wedge shape.The middle part of jig arm 52 is connected with support plate by pivot 54 separately.Near pivot 54, between jig arm, be provided with and open spring 56.Thereby as shown in Figure 1, when send to part by after the position, spring 56 heads on arm opens their front ends.On the contrary, as shown in Figure 4, when sending part in forward position, 52b cooperates the rear end of opening arm 52 with wheel, therefore their front ends is moved towards the other side, makes two arms can clamp a retaining ring.

Bar 24 has axial hole 60, by first axial chamber 12 of its rear end 60a opening to first piston 18 back, and near its front end 60b opening in second axial chamber 14 of second piston, 20 back.For this purpose, be connected with a transverse holes 62 near the front end in hole 60, these hole 62 openings are by the perisporium of the bar 24 behind piston 20.

Because bar 24 is connected with second bar 26, axial hole 60 is also at front end 60b opening freely.Bar 26 also has axial hole 64, and its rear end is connected with the front end 60b of the axial hole 60 of first connecting rod 2.This hole 64 also opening to the 3rd axial chamber 16 behind the 3rd piston 22.For this reason, it is connected with transverse holes 66, and transverse holes 66 openings pass through the periphery of second bar 26 after second piston 22.In addition, the front end 64b in hole 64 seals.

Have a joint 67 to be used to admit the pipe end that infeeds pressure fluid in the back of actuator body 10, this pipe generally is the compressed-air actuated flexible pipe of supply.It is a pipeline 68 that is located at the valve body side and extends axially 28 zones, next door that joint 67 extends forward.The length of pipeline 68 is slightly larger than the length or the axial dimension of first Room 12.For the axial hole speech of connecting rod, this pipeline 68 is the unique long pipelines of apparatus of the present invention.

The device of feed pressure fluid comprises a guiding valve (at Fig. 2, in 5,6 the profile as seen).Notice that for for the purpose of the simplification drawing at Fig. 1, valve not exclusively illustrates in 4.

The slide block 70 of valve can be in primary importance (as Fig. 4, shown in 6) and the second place (as Fig. 1,2, shown in 5) between movable, in primary importance, fluid at least directive in this axial chamber of the piston back that comprises an axial chamber, thereby make and send part 40 to and push away forward, and in the second place, fluid directive at least thereby makes and sends part 40 to and retreat in this chamber of the piston front of an axial chamber.

Slide block 70 can be movable in the transverse holes 72 in the next door 28 that is located between the first, two axial chamber 12,14.As Fig. 2 obviously as seen, the diameter that the hole is parallel to actuator body extends, and separates by next door 28 and centre bore 30.Among Fig. 1 and 4, shown hole 72 does not have slide block 70.

The following describes the various fluid lines that are located in the next door 28.As shown in Figure 1, wall has first pipeline that hole 72 is connected with the pressure fluid feed.More specifically, first pipeline 75 has first section 74, and it radially is connected with the front end of pipeline 68 basically and extends to a plane P, and this plane P is the plane of symmetry parallel with the axis " A " of actuator body, hole 72.Fig. 5,6 section are promptly on this plane P.First pipeline 75 also has second section 76, extends in parallel and makes first section 74 with plane P and be connected with hole 72.For ease of their machined, second section 76 comprises a part 78, and it starts from an end (rear end) in next door 28, and subsequently by plug 80 sealings.The position (schematically) that pipeline 76 enters hole 72 is shown in Fig. 2.

Referring to Fig. 5,6, can see next door 28 and have one second pipeline 82, the aft section of its transverse holes 72 and second axial chamber 14 couples together.Second pipeline 82 has single axial length.Its rear end is led in the transverse holes 72, and its front end leads to the front 28a in next door 28, and this face also constitutes the back of second axial chamber 14.Regardless of second piston 20 position in described chamber, second pipeline, 82 openings are behind described second piston.

Next door 28 comprises one the 3rd pipeline 84, and it couples together the previous section of the transverse holes 72 and first axial chamber 12.As second pipeline 82, the 3rd pipeline also comprises single axial length.Its front end leads to transverse holes 72, and the back 28b in next door 28 is led in the rear end, and this back also constitutes the front end of first axial chamber 12.Therefore, and though first piston 18 in first axial chamber position how, second pipeline 84 all leads to the front of described piston.

Tube wall 28 long enoughs are to hold these pipelines.For example, this length can be two to three times of hole 72 diameters.

Slide block 70 comprises the main body 86 of substantially cylindrical, and it has two convex areas 88,90, is respectively equipped with sealing ring also each other every a segment distance.

In the primary importance (as shown in Figure 6) of slide block, can see first pipeline 75, one section 76 is communicated with second pipeline 82 more specifically, and the 3rd pipeline 84 separates.On the contrary, in the second place (as shown in Figure 5), the first, three pipeline 75,84 is interconnected, and second pipeline 82 separates.

The opening 72a that can give prominence to from the free end of slide block along with transverse holes 72 can see the 3rd, one, two pipelines 84,75 (76) and 82 orders and link transverse holes 72 to its end wall 72b.

The opening that these three pipelines feed in the hole is to separate regularly.Interval between two projectioies 88,90 of slider body is a bit larger tham two intervals between the pipeline.Therefore, along with slide block is sent to towards nose end, because the opening of pipeline 76,82 is between projection 88,90 and be interconnected, and pipeline 84 is separated by projection 90 and other two pipelines.On the contrary, when slide block was far away from the end in hole, the opening of conduit 84,76 was positioned between the projection 88,90, thereby is interconnected, and the opening of pipeline 82 is separated by projection 88 and other two pipelines.

Install following work: 72 end 72b pushes away towards the hole when slide block 70, owing to the air that is positioned at protruding 88 fronts can be accomplished this point through steam vent 92 discharges, the fluid that enters by pipeline 68,74 and 76 can enter the back of second Room 14 through the 3rd pipeline 82 in the next door 28.Therefore the fluid tendency pushes away second piston 20 forward.Simultaneously, fluid enters in the hole 60 of bar 24 through hole 62, and is sent to the rear end of first axial chamber 12, makes fluid also act on the back of first piston 18.Similarly, the fluid that enters through hole 62 is sent to the back of the 3rd piston 22 by hole 64 in another connecting rod 26 and hole 66, thereby also acts on the back of the 3rd piston 22, so fluid acts on three pistons simultaneously, thereby has increased efficient.

Should notice that device for draining fluid is located at the forward part of axial chamber, before piston is shifted onto fully by, discharger just works.To first Room 12, pipeline 84 is communicated with the outside by passing the hole 94 that is used for to the ring 96 of bar 98 guiding of slide block 70.To second Room 14, the fluid that is positioned at the front of chamber is directly directly discharged by the hole 100 of passing this locular wall at front end.At last, the fluid that is positioned at 16 front portions, the 3rd Room can be naturally discharged from this front, chamber because sending part to, supporting arm 46 and encircle 48 between do not establish sealing system.

On the contrary, when slide block 70 is pushed away the end 72a in hole 72, fitted and the positions that limit make by pipeline 68,74 by projection 90 and ring 96,76 air that enter can enter the anterior locations of first axial chamber 12 by the 3rd pipeline 84 in the wall 28.Therefore, the assembly that constitutes of the connecting rod of piston and they is applied fluid in first piston 18 fronts to pusher.In this case, by fluid is acted on other piston and do not need to increase the power that applies.Therefore when

axial chamber

12,14,16 rear portion is interconnected by the hole in the piston rod, at assembly during towards pusher, the air of discharging from described rear portion enters the rear section of second Room 14, be discharged to the outside from this second pipeline 82 by next door 28, when slide block during in the second place, this pipeline 82 directly is communicated with air by tap 92.

The device of control guiding valve comprises the control lever of substantially laterally establishing 102.Be clear that more that as Fig. 2 this bar 102 has the first end 102a that next door 28 zones are connected with actuator body 10.The first end 102a is mounted to and can be pivoted around scratching axle 104, and from Fig. 1,4 are clear that more this pivot 104 extends in parallel with the axis A of valve body basically.The second end 102b of bar 102 cooperates with the free end 99 of slide block 70.

Should notice that this bar directly is connected with next door 28, and only be positioned at the middle region of actuator body.In order to reduce device size, the next door has a transverse groove 29, is wherein putting the first end 102a of bar, and when second end 102 of push rod makes slide block 70 when the end 72b in hole pushes away, bar 102 almost completely is received within the groove 29.Shown in example in, in order to obtain the lever arm of sufficient length, first end of bar and second end mutually from distant.Therefore, bar extend through actuator body periphery more than 1/4th.Therefore this point also can be used for groove 29, and it puts the major part of bar, because bar is crooked, so groove 29 also is crooked.

Device preferably includes elastic device, is used for a slide block 70 its second place of jacking naturally, sends part in this position and pushes up the back.This makes the physical slot of device become possibility in jig arm 52 in the position of non-effect, thereby its action request adds positive effect to slide block 70, and one discharges when bar, and this effect stops.In an illustrated embodiment, elastic device only is made of spring 106.It at first acts on the free-ended inner face facing to the expansion of slide block, and facing to the outside of guide ring 96, this ring is fixed in the hole 72, and the bar 98 of slide block slides therein subsequently.The elastic device of other type also can be provided, for example selectively be located at the end 72b and the helical spring of slide block between the inner that surpasses projection 88 in hole.

Best, this device comprises the device that moves along at least one piston towards displacement stroke end of a direction of displacement damping of sending part at least.Because piston interconnects by connecting rod, in fact this damping unit to by piston, piston rod and the displacement of sending the whole assembly that part constitutes to work.

In the example shown, projection 108 by the more resilient material system of for example rubber and so on of the back that is located at first piston 18 constitutes damping unit, therefore, the assembly that constitutes when piston and their connecting rod is pushed rearward the position of Fig. 1, and projection 108 matches with the back of first Room 12.

Also available projection and so on is contained in the front of a piston (as back piston), so that damping displacement forward.In example, piston 18 comprise a metal-cored 18a and wrapping metal-cored and be provided with the projection the outer shroud 18b by more resilient material system.Best, very accurately limit by sending the position fully forward that part 40 is in the assembly that the most preceding position limits to, so that the actuated position of pawl 52a is also accurately limited.For this purpose, device preferably includes first engagement device, is located near the front end of an axial chamber, also has second engagement device, is located near the described piston front.Therefore, when by piston, piston rod and when sending assembly that part constitutes to and pushing up forward, first and second engagement devices cooperatively interact, thereby limit the top position of described assembly.

Shown in example in, these engagement devices are very simple because first engagement device is made of the front of the 3rd Room 16, this front itself is limited by the rear end 46b of supporting arm 46, and second engagement device is made of the front 22a of the 3rd piston 22.Nature, described engagement device can be located in other the axial chamber.Yet the physical location of arm 46 is regulated by the screw of mounting ring 48 and is determined.Can accurately limit the position of first engagement device like this, and leave the leeway of adjusting.

For the ease of the displacement of piston with avoid the danger vibrated, device preferably includes at least one ring bush 110, is located in the hole 30 in next door 28, and this lining 110 is made by the material with low-friction coefficient.Therefore, lining 110 can cooperate with the neighboring of connecting rod 24, and is convenient to it and slides through the hole.If have, similarly lining 112 also can be located in the hole 36 in additional next door.Lining is set does not naturally hinder sealing ring 32,38 to be located in the hole yet.

The interarea of each piston that cooperates with the axial walls of axial chamber is provided with piston ring 118,120 and 122.The front and back end of connecting rod 24,26 is co-operation by being screwed in together.For the fixing position of described bar on piston, setting-up piece 124 is equipped with in the back of piston 20,22.The rear end of connecting rod 24 is threaded.There is indentation 126 back of first piston 18, is suitable for putting into the hold-doun nut 128 of the rear end that is screwed to bar.Piston is fixing by front that is positioned at piston and the setting-up piece 130 that cooperates with the shoulder of bar with respect to the position of bar.

At last, should notice that actuator body comprises three major components that are made of blind pipe.First pipe 132 limits first Room 12.Its rear wall and sidewall comprise the pipeline that is connected with the supply of pressure fluid.The chamber of second pipe 134 constitutes second axial chamber 14.The rear wall of this pipe constitutes the next door between the chamber 12 and 14.Therefore this wall is provided with porose 72 and each above-mentioned pipeline.This wall is screwed to the front end of first pipe 132.Similarly, the chamber of the 3rd pipe 136 constitutes the 3rd axial chamber 16, and rear wall constitutes the next door 34 between the chamber 14 and 16.This rear wall is screwed to the front end of second pipe 134.Nature be to guarantee the sealing of chamber, sealing ring 138 be located at nipple between each pipe near.

Claims

1. pneumatic actuator means, comprise an actuator body (10), pressure fluid is infeeded the device of the inside of described main body, the first piston (18) that can move in first axial chamber (12) of the rear end that is arranged in actuator body, be arranged in second piston (20) of second axial chamber (14) of the described first axial chamber front with at least one, device also comprises a next door (28) that this two axial chamber is separated, with an axial hole (30) and piston (18,20) connecting rod (24) that connects together and be suitable in described hole, sliding in the mode of sealing, described bar has a hole (60), it at first leads in first axial chamber (12) behind first piston (18), lead to subsequently in second axial chamber (14) behind second piston (20), piston is connected with the part (40) of sending to that is positioned at actuator body (10) front, the device that infeeds pressure fluid comprises a guiding valve (70,72), it is controlled between the primary importance and the second place by control device and moves, primary importance fluid directive in described chamber at least one axial chamber behind the piston so that roof pressure is sent part to forward, and at second place fluid directive at least one axial chamber of the front of the piston of described chamber so that roof pressure is sent part to backward

It is characterized in that described next door (28) has a transverse holes (72), the slide block of guiding valve (70) is received within wherein, one described transverse holes (72) and pressure fluid feed conduit (66,68) first pipeline (74 that couples together, 76), second pipeline (82) that transverse holes (72) and aft section in second axial chamber (14) of second piston (10) back are coupled together, with second pipeline (84) that transverse holes (72) and previous section in first axial chamber (12) of first piston (18) front are coupled together, when the slide block (70) of guiding valve during in primary importance, first and second pipelines (74,76; 82) be interconnected, and separate with the 3rd pipeline (84), when slide block (70) when being in the second place, the first and the 3rd pipeline (74,76; 84) be interconnected, and separate with second pipeline (82).

2. according to the device of claim 1, it is characterized in that described control guiding valve (70,72) device comprises a control lever (102) of horizontally set, the zone of first end (102a) next door (28) of described bar is connected with actuator body (10), and be installed to stingy axle around the axis (104) that extends vertically, and second end (102b) of bar is fit to cooperate with the free end (99) of the slide block (70) of guiding valve.

3. according to the device of claim 1 or 2, it is characterized in that also comprising that the slide block (70) described guiding valve pushes up the elastic device (99) of its second place naturally.

4. according to each device among the claim 1-3, it is characterized in that described transverse holes (72) comprises that an end wall (72b) reaches the opening (72a) away from described end wall, the free end of the slide block of described guiding valve (70) is suitable for protruding above this opening, described the 3rd, first, and second pipeline (84,76,82) link described transverse holes (72) in proper order along the direction of end wall (72b) from opening (72a) towards described hole (72).

5. according to each device among the claim 1-4, it is characterized in that also comprising at least one direction of displacement of sending part to along described, at the device (108) of the motion of at least one piston of the end of displacement stroke damping.

6. according to each device among the claim 1-5, it is characterized in that also comprising and be located at described axial element (12,14,16) near first engagement device (46b) in the front end of (16), and being located near second engagement device (22a) of the piston piston front that is arranged in described chamber, first and second engagement devices acting in conjunction mutually limit the described extreme position that part (40) can be sent to of sending to.

7. according to each device among the claim 1-6, it is characterized in that also comprising at least one ring bush (110), be located in the axial hole (30) in the next door, in the described lining (110) material of low-friction coefficient make and with connecting rod (24) acting in conjunction.

8. according to each device among the claim 1-7, what it is characterized in that also comprising a front that is arranged in second axial chamber can be at movable the 3rd piston (22) of the 3rd axial chamber (16), separate the described second and the 3rd axial chamber (14 for one, 16) and the additional next door (34) of an axial hole (36) arranged, be connected the second and the 3rd piston (20 with one, 22) and be suitable for the additional connecting rod (26) that the sealing means in described axial hole slides, described connecting rod has a hole (64) and first, two pistons (18,20) hole (60) in the connecting rod between (24) connects, and leads in the 3rd axial chamber (16) behind the 3rd piston.