GB2311356A

GB2311356A - Vehicle suspension arrangement

Info

Publication number: GB2311356A
Application number: GB9705501A
Authority: GB
Inventors: Masayoshi Azagami; Hideyuki Takizzawa; Takashi Okada; Hideo Tamamori; Toyohiko Imakita; Ian Robert Bennett
Original assignee: Messier Dowty Ltd; NABCO KK; ZAIDANHOJIN RAILWAYS INTEGRATE
Current assignee: Safran Landing Systems UK Ltd; NABCO KK; ZAIDANHOJIN RAILWAYS INTEGRATE
Priority date: 1996-03-19
Filing date: 1997-03-17
Publication date: 1997-09-24
Anticipated expiration: 2017-03-17
Also published as: JPH09254785A; GB2311356B; JP3278346B2; GB9705501D0

Abstract

A wheel for supporting a magnetic vehicle or aircraft is raised and lowered by a piston and cylinder arrangement, and damped by a coaxial spring and damper cylinder arrangement. The wheel is moved by a hollow piston rod 54 and piston 56 sliding in a main cylinder 52, and is locked in the extended state. An outer coaxial cylinder 150 demarcates two oil chambers 810, 820; resistance being governed by a proportional valve 180. Spring discs 70, or a coil, surround the cylinder.

Description

LEG SYSTEM AND DAMPER-FITTED ELEVATOR CYLINDER This invention relates leg systems provided with wheel elevation functions. In particular, it concerns an effective technique for improving passenger comfort in magnetic levitation carriages in which space is severely restricted. Also, this invention concerns a technique in which dampers for cushioning load variations are incorporated in the elevator cylinders for raising and lowering the wheels which receive the load along the axial directions of the cylinder main bodies.

Elevator cylinders are important for, for instance, the leg systems of magnetic levitation carriages or leg systems for other vehicles or aircraft. Among magnetic levitation carriages, for example, in carriages which use electro-magnetic induction systems, levitation running is performed at high speed. However, at low speed, running on wheels is performed because great levitation power cannot be obtained. The leg systems are used to achieve the two running modes of levitation running and wheeled running. In such leg systems, the elevator cylinders have elevator functions for raising and lowering the wheels. However, with leg systems, apart from the raising and lowering functions, a cushioning function is required to improve passenger comfort.

Normally, the cushioning function is achieved by dampers or spring mechanisms.

An improved leg system is required to be superior in oth the functions of raising/lowering and cushioning. However, in practice, simple installation on the bogie, etc. (simplicity of installation), is also important.

From the viewpoint of simplicity of installation, a small number of parts for installation to the bogie, etc. is desirable. In addition, from the point of reducing the number of installation parts, a leg system designed to combine in one body the whole of the elevator cylinder, the damper and the spring mechanism (for instance, Laid-Open Patent No. Heisei 6 (1994) 21130 Gazette), is more desirable than the separate installation of a damper and an elevator cylinder and positioning a spring mechanism on the outer periphery of one or the other of these (for instance, Laid-Open Patent No. Heisei 5 (1993) - 131921 or Laid Open Patent No. Heisei 6 (1994) - 219270 Gazettes).

Here, while considering the above investigation results, we have concentrated in particular on the damper which concerns passenger comfort. The damper is an oil damper which obtains its resistance based on the oil flow resistance through a small hole.

From the aspect of passenger comfort, it is preferable to ensure that there is a proportional relationship between the piston speed of the damper and the resistance, in other words a straight line damping characteristic. However, when attempting to incorporate this desirable configuration of damper with an elevator cylinder, hitherto, a composition has mainly been adopted which aligns the elevator cylinder and the damper in series on the same axial line (for instance, see the above-mentioned Laid-Open Patent Heisei 6 21130 Gazette).

However, in this serial alignment on the same axial line, there is the unavoidable problem of the length in the axial line direction becoming greater so that the space occupied by the system becomes greater. In order to solve this space problem, it is vital in the case of the leg system for the installation space required to be limited.

According to a first aspect of the present invention, there is provided a leg system as claimed in appended claim 1.

It is thus possible to provide a leg system which includes a damper-fitted elevator cylinder of which the length in the axial line direction is comparatively small, despite the fact that the elevator cylinder and the damper are incorporated.

It is further possible to provide a leg system which is simple to install and, moreover, which can restrict the required space to the minimum.

Moreover, it is the aim of this invention to provide a damper-fitted elevator cylinder which has an effective damping characteristic.

Furthermore, the aim of this invention is to provide an elevator cylinder in which a spring mechanism and part of the members can be used in common.

According to a second aspect of the present invention, there is provided an elevator cylinder as claimed in appended claim 4.

Preferably, a second cylinder member is provided on the outer periphery of the cylinder main body of the elevator cylinder coaxially with the cylinder main body. Oil chambers and are formed between the outer periphery of the cylinder main body and the second cylinder member. A Damper is constructed using those oil chambers. The Damper functions so that it cushions the load variations on the elevator cylinder applied in its axial line direction. With this construction, the parts of damper are included in the length in the axial line direction of the cylinder main body. Therefore, despite its being a damper-fitted elevator cylinder, the length of the elevator cylinder in its axial line direction is the same as that of the elevator cylinder itself.

Preferably, in addition to the damper, a spring mechanism for receiving the above load may also be provided incorporated in the elevator cylinder. In such an arrangement, the spring mechanism can be positioned on the outer periphery of the cylinder main body. Advantageously, the Spring mechanism is composed of a first spring shoe supported by the cylinder main body at a rod end side; a second spring shoe position-regulated on the cylinder main body at the head end side and a compression spring supported between these first and second spring shoes. In order to cope with the deformation of the compression spring, one or other of the first and second spring shoes may be constructed so that it will travel in the axial line direction of the cylinder main body. From that viewpoint, the second shoe on the head end side, to which the load from the bogie side is directly applied, is designed so that it can travel. At the same time, a second cylinder member may be designed so that it doubles as the second spring shoe. This is because second cylinder member, which encloses oil chambers and, and the second spring shoe which supports compression spring have in common the point of being able to travel in the axial line direction of cylinder main body.

Also, for the first spring shoe, an outward flange part of cylinder main body may be used. As a compression spring arranged on the outer periphery of cylinder main body, a coil spring or a disc spring may be used. With a disc spring, multiple disc springs can be used in series, one on another. Also, with a coil spring, a single coil spring can be used, or multiple coil springs (for instance, four) can be used by arranging them distributed along the periphery direction of the cylinder main body. It is desirable to obtain a damping characteristic which has superior linearity by applying pre-loading to these compression springs.

Advantageously, a passage linked to the oil chamber of the damper t is provided inside the second cylinder member which doubles as the second spring shoe. A throttle valve, preferably a proportional valve, which is linked to the passage can be externally installed on the outer periphery of the second cylinder member. This configuration is the optimum for obtaining a suitable damper function without increasing the space in the axial line direction.

A damper-fitted elevator cylinder constituting an embodiment of this invention can be applied to magnetic levitation carriages or the leg systems of aircraft. In the most desirable configuration of this invention, the elevator cylinder is also provided with a spring mechanism on the outer periphery of the cylinder main body, in addition to the damper. For that reason, an L-shaped leg system can be constructed which links in an Lshape elevator cylinder, which includes the damper and the spring mechanism, and trailing arm, which itself links an axle side of wheel and the bogie side. This L-shaped leg system has a short length in the axial line direction of the elevator cylinder. This is advantageous from the installation space aspect. Moreover, it is superior in that there may be as few as two points of attachment with the bogie.

The present invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of an embodiment of the leg system of this invention; Figure 2 is a front elevation of the leg system in Figure 1; Figure 3 is a cross-section of the elevator cylinder in the leglowered state; Figure 4 is a cross-section of the elevator cylinder in the legraised state, and shows a cross-section along the line 4 - 4 of Figure 3.

Figure 5 is a cross-section of the essential parts, showing the machine locked state due to the locking mechanism; Figure 6 is a cross-section of the essential parts, showing the unlocked state due to the locking mechanism; Figure 7 is a cross-section of Figure 4 along the line 7 - 7; Figure 8 is a drawing of the elevator cylinder of Figure 4 viewed from the axial direction; Figure 9 is a cross-section showing an example of an oil reservoir; Figure 10 is another cross-section along the line 10 - 10 of figure 9; Figure 11 is a front elevation showing an example of a proportional valve; and Figure 12 is a cross-section of the proportional valve of Figure il.

Figures 1 and 2 show the overall construction of Lshaped leg system 10. "L-shaped" describes the support mode formed by a trailing arm 20, which extends almost horizontally, and an elevator cylinder assembly 30, which extends in a substantially vertical direction from the end of trailing arm 20.

Trailing arm 20 is an arm which links the axle 22 side and the bogie 24 side. One end, 20a, is supported on the end of axle 22 so that rotation is possible. Also, the other end, 20b, is supported so that rotation is possible on the side of bogie 24 by lower bracket 23 and pin 25. Thus, the L-shaped leg system 10 has two installation parts with regard to the bogie 24 side (the end of trailing arm 20 and the end of elevator cylinder assembly 30).

A Wheel 40 is fitted round axle 22 for wheel running.

The Wheel 40 is composed of tyre 42 (for example, nitrogen gasfilled) on its outer periphery and a metal wheel on the inner periphery which supports the tyre 42. The metal wheel is provided with an incorporated external auxiliary wheel 44 to cope in the event of a tyre puncture. Also, a vertical arm 46, is provided on the side of the wheel 40. This arm 46 is an arm for supporting a guide wheel 47. A Wheel disc brake system 48 is also fitted inside the wheel 40.

A lower end 30d of the elevator cylinder assembly 30 is linked to the axle 22 side via the trailing arm 20. An Upper end 30u is linked to the bogie 24 side through an upper bracket 33.

rhe linkings of elevator cylinder assembly 30 are pin connections, in the same way as in the case of the trailing arm 20. Therefore, trailing arm 20 oscillates about its supporting point on the lower bracket 23 side in response to the expansion and contraction of elevator cylinder assembly 30. Thus, the trailing arm 20 can vertically raise and lower wheel 40 which turns on axle 22. In Figures 1 and 2, the lowered state of wheel 40 (wheel running) is shown by solid lines, while the raised state of the wheel 40 (levitation running) is shown by chain lines.

The installation space for a leg system 10 is significantly restricted since the propulsion mechanism for a magnetic levitation carriage (such as superconducting magnets which generate the propulsion and levitation power, and the cooling-related devices for the superconducting magnets) occupies a large space. In Figures 1 and 2, the outer frame shown by the chain line is the permitted installation space for the leg system 10. That installation space is greatly restricted on the points of the height from the road surface G to the bottom of the bogie 24 and the distance in the width direction of the bogie 24. From the viewpoint of this installation space, there is a requirement to reduce the length in the axial direction of elevator cylinder assembly 30. The main body of the elevator cylinder assembly 30 is an elevator cylinder 50, which is an oil pressure actuator. A number of accessories or auxiliary mechanisms are incorporated with the elevator cylinder 50. The Elevator cylinder 50, which is the main body, is described in further detail below with reference to separate drawings. In order to make that description more understandable, here, the types of mechanism and how elevator cylinder system 30 incorporates them around the periphery of the elevator cylinder 50 are described. The Elevator cylinder 50 itself includes a cylinder main body 52 and a piston rod 54 in which the axial line coincident with that of the cylinder main body 52. An adjusting screw mechanism 60 is provided at the head end side of the cylinder main body 52 for adjusting the length in the axial direction of the elevator cylinder assembly 30. Also, in the leg system 10, a spring mechanism 70, which includes a compression spring, and a damper 80, which includes oil chambers, are respectively positioned on the outer periphery part of the cylinder main body 52.

Figures 3 and 4 show an example of an elevator cylinder which uses disc springs. Figure 3 is a cross-sectional constructional drawing showing the extended state of the piston rod 54 (the leg in a lowered state; i.e. the state corresponding to wheeled running). Figure 4 is a cross-sectional constructional drawing showing the contracted state of the piston rod 54 (the leg raised state; i.e. the state corresponding to levitation running).

The internal diameter of the cylinder main body 52 of the elevator cylinder 50 is the same from rod end side 52r to head end side 52h. In the cylinder main body 52, an outward flange 522 is provided on the outer periphery of rod end side 52r, and a screw cap 524 is ,provided on the end of head end side 52h, respectively.

One end of the rod end housing 53 butts against one side of the outward flange 522. Also, a rod bearing 55 is screwed into the open part of the other end of the rod end housing 53. The rod searing 55 guides the piston rod 54 which strokes in the axial direction. Moreover, penetration of foreign material into the cylinder system 50 is prevented by dust shield 55s.

The inside of the piston rod 54 is hollow, and a coupling 58, which links rod end member 57 and the piston 56 side is provided in the centre part. The Rod end member 57 is itself screwed to a press-in cap 59 of the piston rod 54 side, and is locked by a nut 57n. This lock-nut 57n, as can be seen from Figure 4, also supports a dock 12d for operating a leg-raised detector switch 12. Apart from first supporting unit 510, which is pin-connected to the axle 22 side, a leg-lowering port 572 is provided in the rod end member 57. Port 572 connects with the inside of cylinder main body 52 through a coupling 58. The Piston 56 is incorporated with the rod 54 at the end of the head end side of the piston rod 54. The Piston 56 is of slightly larger diameter than the rod 54, and a piston ring 56s is provided on its outer periphery. The Piston ring 56s divides the inside of cylinder main body 52 into a first control chamber 91 on the rod end side and a second control chamber 92 on the head end side by its sealing action. The Leg-raising port 532, provided in rod end housing 53, links with first control chamber 91. When fluid pressure, such as oil pressure is supplied to first control chamber 91 through the port 532, the leg system 10 retracts the piston rod 54 of elevator cylinder 50 into the cylinder main body 52 so that the leg-raised state shown in Figure 4 is achieved. On the other hand, when oil pressure is supplied to the second control chamber 92 through the leg-lowering port 572, which is part of the rod end member 57, the leg system 10 extends the piston rod 54 so that the leg-lowered state shown in Figure 3 is achieved. When in this leg-lowered state, a locking mechanism 200 on the inner periphery of piston 56 locks the piston rod 54 to the cylinder main body 52.

Figures 5 and 6 respectively show the machine locked state and the unlocked state due to the locking mechanism 200.

The Locking mechanism 200 is a 2-stage machine lock. It operates stably even at heavy loadings, such as may be provided by a magnetic levitation carriage. The Locking mechanism 200 includes a cup-shaped carrier member 202. The central part of carrier member 202 is supported by the end of the coupler 58, while its outer periphery is secured to the inner periphery of piston 56 by a stopper ring 204. A first locking piston 210 and a second locking piston 220 are respectively provided on the outer periphery and the inner periphery of the carrier member 202. Each locking piston 210 and 220 is pushed in the rod end direction by a first spring 212 and a second spring 222 respectfully. These first and second locking pistons 210 and 220 put each of first and second segments 214 and 224 into the machine locked and unlocked states by cam actions which use their tapers. Multiple segments 214 and 224 are aligned in the peripheral direction and are supported so that they can move in the radial direction.

The first locking piston 210 on the outer periphery of the carrier member 202 is pushed in the rod end direction by the first spring 212. For that reason, the first segment 214 is pushed in the outer diameter direction by the taper. Thus, when the piston 54 comes to its stroke end, the first segment 214 moves outward to face a lock seat 230, which is inserted in the cylinder main body 52. At the same time, the second locking piston 220 on the inner periphery of carrier member 202 is pushed in the rod end direction by the second spring 222. For that reason the second segment 224, which is fitted on the outer periphery of the second lock piston 220, is pushed in the outer diameter direction by the taper. When the first segment 214 moves outward, the second segment 224 also moves outward and engages in a groove in the first locking piston 210. Next, the second locking piston 220 advances further in the rod end direction, and the parallel part of its outer periphery prevents the reverse movement of the second segment 224 in the centre direction. Therefore, even if, for instance, the oil pressure of the elevator cylinder 50 is lost, neither segment 214 nor 224 will disengage. This is the machine locked state. When the piston rod 54 reaches the extension stroke end, the leg lowered detection switch 14 of rod end housing 53 is operated by lever 14a. The centre part of lever 14a itself is an oscillation fulcrum, and is designed so that one end touches the switch 14 while the other end touches the step of the piston 56.

On the other hand, when operating under its own weight, the first segment 214 is pushed in the inner direction by the taper of the lock seat 230. In accompaniment to this, the first locking piston 210 is pushed to the head end side by the taper of the inner diameter side of first segment 214. By this means, the second segment 224 is pushed in the inner direction by the taper.

Thus, when oil pressure is supplied to first control chamber 91 from the leg raising port 532 in response to leg-raising, the second locking piston 220 is pushed to the head end side and the second segment 224 engages in the groove of its outer diameter part. By this means, the catching of first locking piston 210 is eliminated. Therefore, the first segment 214 overcomes the first spring 212 and pushes the first locking piston 210 in the head end direction. Then, the first segment 214 itself slides under the piston 56, and to complete the release.

With the leg system 10 of this invention, in order to improve passenger comfort, the damper 80 and spring mechanism 70 are incorporated with the elevator cylinder 50 on the outer periphery of the cylinder main body 52 of elevator cylinder 50.

Furthermore, the leg system 10 shown in the drawings makes partial common use of parts of the damper 80 and parts of the spring mechanism 70. Therefore, the overall number of parts is reduced.

The second cylinder member 150 is provided coaxially with the cylinder main body 52 on the outer periphery of cylinder main body 52. The second cylinder member 150 is also both the member which divides the oil chambers for the damper 80 and one of the spring shoes of the spring mechanism 70. In the spring mechanism 70, multiple disc springs 750 are positioned on the outer periphery of second cylinder member 150 as a compression spring. The multiple disc springs 750 are aligned in series in the axial line direction, with their front and reverse sides changing alternately. The disc springs positioned at the two ends of these multiple disc springs 750 are respectively supported by the outward flange 522 of cylinder main body 52 and the outward flange 152 of second cylinder member 150. That is to say, each of outward flanges 522 and 152 functions as a spring shoe for disc springs 750. First spring shoe 522 on the rod end side is incorporated with the cylinder main body 52. Therefore, there cannot be any relative movement between it and cylinder main body 52. As opposed to this, the second spring shoe 152 on the head end side is moveable in the axial line direction with regard to the cylinder main body 52. By this means, it responds to the deformation of disc springs 750. Also, when each disc spring 750 deforms, it moves so that the diameter of its inner periphery contracts and the diameter of its outer periphery expands. When it performs this kind of movement, in particular, support of the disc springs 750 positioned at the two ends is devised to reduce the sliding resistance at the first and second spring shoe 522 and 152 parts. For instance, a copper shoe ring 770 is inserted in the stainless steel cylinder main body 52. Also, for instance, it is made a copper - hard steel contact construction by pressfitting supporting pins 780 to lightweight titanium disc springs 750. The disc springs 750 positioned at the two ends are made to support the inner periphery side and reduce the load of the spring shoe side. Also, the second cylinder member 150, which includes the second spring shoe 152, can be positionally adjusted by the screw cap 5,24. By this means, a specified pre-loading can be applied to the disc springs 750.

A ring fitting part 526 is provided on the outer periphery of cylinder main body 52 close to its centre. The ring fitting part 526 is a part for fitting seal ring 526s and guide ring 526g. Together with the guide ring 524g, fitted on the outer periphery of screw cap 524, it guides the movement of the second cylinder member 150. Here, seal rings 524s on the inner and outer peripheries of screw cap 524, seal ring 152s on seal fitting part 152, and seal ring 526s on ring fitting part 526 are provided respectively. Therefore, two adjacent chambers, in other words a first oil chamber 810 and a second oil chamber 820 are demarcated in the axial line direction of seal fitting part 152. From the arrangement of leg system 10, the first oil chamber 810 is the lower chamber and second oil chamber 820 is the upper chamber.

The thickness of the part from the ring fitting part 526 of the cylinder main body 52 to the end of the head end side is thicker than that of the part on the rod end side. This is in order to cope with the pressures generated in the first and second control chambers 91 and 92. The second oil chamber 820 is linked to an oil reservoir 160 through a passage inside member 150, which is a spring shoe.

Figures 9 and 10 show an example of an oil reservoir 160. The oil reservoir 160 is composed of reservoir part 162 and a valve housing 164 which is incorporated with the reservoir part 162. A piston 162p, which is energised by a spring 162c, is provided inside the reservoir part 162. The piston 162p together with the reservoir part 162 demarcate a reservoir chamber of, for instance, about 25 cc. Also, a check valve 165 is provided inside the valve housing 164. The check valve 165 is designed to be able to replenish oil from the reservoir chamber toward the passage 153 side while cutting off the flow toward the reservoir chamber from the passage 153 side. A filling valve 167, which is the oil filling port, is provided in part of valve housing 164.

In the same way as the oil reservoir 160, a system which is proportional valve 180 is externally fitted on the outer periphery of the second cylinder member 150. The proportional valve 180 ensures the linearity of the damper characteristic, and thus further improves passenger comfort. The proportional valve 180 is positioned 900 away from oil reservoir 160 around the axis (in particular, see Figure 8). Figures 11 and 12 show an example of the proportional valve 180. The proportional valve 180 applies resistance to the flow from the first oil chamber 810 to the second oil chamber 820 or in the reverse direction. Thus, it provides a pair of proportional throttle valves of the same construction between the first and second oil chambers 810 and 820. Diameter direction passage 158, provided in the second cylinder member 150, links each oil chamber 810 and 820 to the proportional valve 180 side. The housing 184 of proportional valve 180 provides a dividing wall 184w at its centre. Thus, there is a left/right symmetrical construction about the centre of dividing wall 184w. The poppets 185, provided with grooves 185c, and springs 187, which energise poppets 185, are provided inside the left a9d right housings. Poppets 185 and springs 187 function as the above proportional throttle valves. It will be seen that, as shown in Figure 12, similar piping connections are made to the pair of proportional throttle valves. Bolts 188 in the bottom of housing 184 are the bolts for external fitting. Also, part 181, which projects diagonally from housing 184, is an air bleeder mechanism.

Next, let us turn our attention to the head end part of cylinder main body 52. In adjusting screw mechanism 60, for adjusting the length (in other words, the height) in the axial direction of the elevator cylinder assembly 30, is provided at this head end part. This height is the length between the first supporting unit 510 on the rod end side and the second supporting unit 520 on the head end side. Thus, the mechanism itself which adjusts this can be suitably arranged anywhere from the first supporting unit 510 to the second supporting unit 520.

Preferably, as in adjusting screw mechanism 60, it may be arranged at the head end part. By this means, adjustment can be made from within bogie 24.

The adjusting screw mechanism 60 is composed of: a head end housing 62 which is incorporated with second cylinder member 150; a height adjusting nut 64 which is screwed to the outer periphery of housing 62; a head end part 66 which is supported on height adjusting nut 64 via a step part; and a nut 68 which is screwed on the outer periphery of head end member 66, and is designed to lock the height adjusting nut 64.

Therefore, by turning height adjusting nut 64, the position of head end member 66 on the axial line, in other words the position of second supporting unit 520, can be adjusted.

Claims

1. A leg system comprising: a trailing arm of which one end is linked to an axle which supports a wheel, while the other end is installed on a bogie; an elevator cylinder which is linked to the trailing arm and which performs raising and lowering of the wheel; and a damper and spring mechanism for cushioning load variations between the wheel and the bogie, and in which a second cylinder member is provided coaxially with that cylinder main body on the outer periphery of the cylinder main body of the said elevator cylinder; demarcating a chamber between the outer periphery of the cylinder main body and the second cylinder member and a damper is formed using that chamber.

2. A leg system as claimed in Claim 1 in which the parts installed on the said bogie side are the two places of the other end of the said trailing arm and the end of the said elevator cylinder.

3. A leg system as stated in Claim 1 or Claim 2 in which the said spring mechanism includes a coil spring or a disc spring which is positioned on the outer periphery of the said cylinder main body.

4. An elevator cylinder which is provided with: a cylinder main body which has a rod end at one end in the axial direction and a head end at the other end; a piston which demarcates control chambers inside that cylinder main body and travels in the said axial direction according to the supply of fluid pressure to those control chambers; a piston rod which is connected as one with that piston, extends on the rod end side from the piston part, and of which the extended end is positioned outside the said cylinder main body, and receives the load along the said axial direction through a first supporting unit for the end side of the piston rod which is positioned on the rod end side and a second supporting unit which is positioned on the head end side; and a damper-fitted elevator cylinder which provides a second cylinder member coaxially with that cylinder main body on the outer periphery of the said cylinder main body, demarcates chambers between the outer periphery of the cylinder main body and the second cylinder member and forms a damper for the said load using those chambers.

5. An elevator cylinder as claimed in Claim 4 in which the chambers are composed of an upper chamber and a lower chamber which adjoin each other in the axial direction, and in which there is a throttle valve between the upper chamber and the lower chamber.

6. An elevator cylinder as claimed in Claim 5 in which the said throttle valve is positioned on the outer periphery of the second cylinder member.

7. An elevator cylinder as claimed in Claim 4 in which there is also an adjusting screw mechanism, for adjusting the distance between the first supporting unit and the second supporting unit, between the second cylinder member and the second supporting unit.

8. An elevator cylinder as claimed in Claim 4 in which there is a spring mechanism on the outer periphery of the said cylinder main body which receives the said load, and this spring mechanism is provided with: a first spring shoe which is supported on the cylinder main body at the rod end side; a second spring shoe which is position-regulated with regard to the cylinder main body at the head end side and a compression spring which is supported between these first and second spring shoes.

9. An elevator cylinder as claimed in Claim 8 in which the second cylinder member has the dual role of the second spring shoe.

10. An elevator cylinder as claimed in Claim 9 in which there is a passage linked to the said chambers inside the second cylinder member which doubles as the second spring shoe, and a throttle valve which leads to that passage is positioned on the outer periphery of the second cylinder member.

11. An elevator cylinder as claimed in Claim 4 in which the said elevator cylinder is provided with a locking mechanism which locks the piston rod in the extended state.

12. An elevator cylinder as claimed in any of Claims 8 to 10 in which the said cylinder main body is respectively provided with an outward flange at the rod end side and a screw cap at the head end side, and in which the outward flange functions as the first spring shoe, while the screw cap position-regulates the second spring shoe.

13. An elevator cylinder as claimed in any one of claims 4 to 12, in which the chambers are oil filled.