Shock absorber construction

A shock absorber which can be used in tension or compression and which is adjustable in either mode of operation including a casing having first and second ends, a piston rod extending through the first end and having a piston head mounted thereon within the casing, a reversible check valve structure mounted in a cartridge for insertion into the second end, a spring within the cartridge, an adjustable member for exerting a force on one end of the spring, and a check valve member biased by the opposite end of the spring.

BACKGROUND OF THE INVENTION 
The present invention relates to an improved shock absorber which includes 
structure which permits it to be selectively built for use either in 
tension or compression and which is adjustable in either mode. 
SUMMARY OF THE INVENTION 
It is one object of the present invention to provide an improved shock 
absorber which can be set up to operate either in tension or compression. 
A related object of the present invention is to provide an improved shock 
absorber in which the conversion between operation in tension or 
compression can be done simply by merely reversing certain parts thereof. 
A further related object of the present invention is to provide an 
improved shock absorber in which the resisting force of the shock absorber 
can be adjusted in either mode of operation in an extremely simple manner. 
Other objects and attendant advantages of the present invention will 
readily be perceived hereafter. 
The present invention relates to a shock absorber comprising a casing 
having first and second ends, a chamber in said casing for containing 
fluid, a piston head in said chamber, a piston rod mounting said piston 
head and extending through said first end, means at said first end of said 
casing for supporting said piston rod for sliding movement, bleed means in 
said casing for providing said fluid to said chamber from an area external 
of said casing, and reversible check valve means mountable in first and 
second positions on said casing for causing said shock absorber to provide 
shock absorption in a first direction of piston movement when said check 
valve means is in said first position and for causing said shock absorber 
to provide shock absorption in a second direction which is opposite to 
said first direction when said check valve means is in said second 
position. 
The various aspects of the present invention will be more fully understood 
when the following portions of the specification are read in conjunction 
with the accompanying drawings wherein:

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The improved shock absorber 10 of FIGS. 1-3 includes a molded plastic 
casing 11 having an integral molded end wall 12 having an integrally 
formed seal 13 surrounding bore 14 which slidingly receives piston rod 15 
in sealing engagement. The seal structure is shown in U.S. Pat. No. 
4,265,344, which is incorporated herein by reference but which forms no 
part of the present invention. A piston head 16 is suitably secured to the 
end of piston rod 15. An end wall 17 is suitably secured at the end of 
casing 11 opposite to end wall 12, and a reversible pressure controlling 
structure 19 is located in a bore 20 in end wall 17 so as to permit the 
shock absorber to be set up to operate in compression or tension, the 
compression being when piston rod 15 moves in the direction of arrow 21 
and tension being when piston rod 15 moves in the direction of arrow 22. 
As set up in FIG. 1, the shock absorber check valve structure is in 
position to operate in tension, that is, when piston rod 15 moves in the 
direction of arrow 22 when subjected to shock loads. 
The check valve structure 19 is located in bore 20 and includes a spring 23 
having one end bearing against shoulder 24 which is located proximate bore 
25. The other end of spring 23 bears against check valve member 26 which 
presses against annular seat 27 at the end of hollow threaded sleeve 29 
which is threadably received in tapped bore 30. Sleeve 29 has a hexagonal 
bore 28 in the end thereof for receiving an Allen wrench. By adjusting the 
axial position of sleeve 29 within bore 30 by use of the Allen wrench, the 
force which spring 23 exerts on check valve member 26 can be varied to 
thereby vary the resisting force which the shock absorber will provide 
when piston rod 15 is moved in the direction of arrow 22. Any air in 
chamber 31 to the right of piston 16 will be expelled through orifice 32 
in end wall 12. It will be appreciated that there is a slight clearance 
between the outer periphery of piston head 16 and the inner surface 33 of 
casing 11 so that the pressure on opposite sides of piston head 16 will 
tend to equalize, as this action is necessary when the shock absorber 
operates in compression. 
If it is desired to cause the shock absorber 10 to operate in compression, 
that is, to provide the shock absorption when piston rod 15 is subjected 
to forces in the direction of arrow 21, it is merely necessary to unscrew 
sleeve 29, remove check valve member 26 and spring 19, reinsert the check 
valve member 26 so that it bears against shoulder 24 and covers orifice 
25, reinsert spring 23, and thereafter screw in sleeve 29 until the proper 
spring force on check valve member 26 is obtained. While the shock 
absorber is primarily intended to be pneumatic, it will be appreciated 
that it can be immersed in a liquid to operate in the same manner as in 
air. The shock absorber is therefore being considered to be of the fluid 
type. 
A modified shock absorber 10' is shown in FIGS. 4 and 5. This modified form 
differs from the embodiment of FIGS. 1, 2 and 3 only in that a check valve 
cartridge is used rather than the separate spring and check valve of FIGS. 
1, 2 and 3. 
The shock absorber 10' of FIG. 4 has cartridge 34 oriented therein so that 
it will operate in tension, that is, when the piston rod is moved in the 
direction of arrow 35. The cartridge 34 includes a housing 36 which is 
preferably fabricated of molded plastic, and which is received in bore 37 
of end wall 17. An annular presser member 39 has a central portion which 
is slidably received in orifice 40 in the end wall of cartridge 36. The 
end 41 of presser member 39 abuts shoulder 42 of the end wall 17. One end 
of spring 43 bears against the end 44 of the presser member and the other 
end of spring 43 biases ball check valve 45 against a seat on cartridge 
end wall 46 so as to obstruct bore 47. An annular retaining and adjusting 
sleeve 49 bears against housing end wall 46 and sleeve 49 has threads 50 
on the outside thereof which are received in threaded relationship in 
tapped portion 51 in neck 52 extending outwardly from end wall 17. It will 
readily be appreciated that the force which spring 43 exerts on ball check 
valve 45 is determined by the position of sleeve 49 inasmuch as this will 
determine the amount that presser member 39 compresses spring 43. 
If it is desired to cause shock absorber 10' to operate in compression, 
that is, to absorb shocks when the piston rod 15 is moved in the direction 
of arrow 53, it is merely necessary to reverse the position of cartridge 
34 to the position shown in FIG. 4. This can be achieved by unscrewing 
sleeve 49, removing cartridge 34, turning cartridge 34 end-for-end, 
reinserting cartridge 34 into bore 37, and reinserting sleeve 49 until the 
desired force is obtained on spring 43. In the reversed position the end 
portion 54 of retaining sleeve 49 will bear against the end 41 of presser 
member 39 so as to provide the capability of adjusting the compression of 
spring 43, to thereby adjust the resistive strength of the shock absorber. 
Retaining sleeve 49 has a hexagonal bore 48 therein to receive an Allen 
wrench for removing and replacing sleeve 49. 
In FIG. 6 graphs 55, 55a and 55b depict 90% efficient force-stroke diagrams 
for various valve settings. Each graph shows the constant force from the 
pressure responsive valve at various positions of the pressure responsive 
valve pressuring screw for air velocity. Graph 56 shows the force at 
various portions of the stroke for a simple needle valve bleeder orifice 
of conventional design at one velocity with an efficiency of only 60%. 
In FIG. 7 a further embodiment of the present invention is disclosed. The 
shock absorber 10a is constructed identically to that disclosed in FIG. 1 
except for the structure at the left end. In the embodiment of FIG. 7 a 
combined end wall and cartridge 60 is press-fitted into the end 61 of 
cylinder 62. A seat 63 is provided at the end of bore 64 for seating ball 
check valve 65 which is biased by spring 66 to overlie bore 67. A sleeve 
69 is threadably received within tapped bore 70 to adjust the compressive 
force on spring 66. A hexagonal bore 71 within sleeve 69 receives an Allen 
wrench for adjustment purposes. 
As the check valve is set up in FIG. 7, the shock absorber will operate in 
compression, that is, when the piston moves in the direction of arrow 72. 
If it is desired to have the shock absorber operate in tension, sleeve 69 
may be removed from bore 70 to permit the threadable insertion of a puller 
member (not shown) into tapped bore 70. The puller member is used to 
remove combined end wall and cartridge 60 from cylinder 62, which is 
thereafter reinserted into end 61 with a press fit after sleeve 69 has 
been adjusted to provide the proper force on ball check valve 65. After 
combined end wall and cartridge 60 has thus been reversed, the shock 
absorber 10a will operate in tension, that is to provide shock absorption, 
when a force in the direction of arrow 73 is applied to the piston. 
In FIG. 8 a modification of the embodiment of FIG. 7 is disclosed. The 
shock absorber 10b includes a combined end wall and cartridge 74 which 
includes an internal construction which is identical to cartridge 60 of 
FIG. 7. However, the outside of plastic cartridge 74 has a helical thread 
75 molded thereon. Cartridge 74 may be inserted into end 61 of cylinder 62 
by either pressing it in the direction of arrow 76, or by screwing it into 
position by applying a screwdriver to screwdriver receiving slot 77. If it 
is desired to reverse the position of cartridge 74, it is merely necessary 
to unscrew it by applying a screwdriver to screwdriver slot 77 and 
thereafter reinsert cartridge 74 in position by applying a screwdriver to 
screwdriver slot 79. In the embodiment of FIG. 8 it is not necessary to 
change the position of sleeve 69 in order to remove cartridge 74. 
In FIGS. 9 and 10 a further embodiment of the present invention is 
disclosed. The shock absorber 10c is identical to that shown in FIG. 1 
except for the structure at the end 81 of the cylinder. End wall 80 is 
press-fitted into the end 81 of the cylinder and need not be removed for 
either varying the operating force of the check valve or for reversing the 
check valve operation for permitting the shock absorber 10c to operate 
either in tension or compression. 
End wall 80 includes a seat 82 proximate bore 83. A ball check valve 84 is 
biased onto seat 82 by one end of spring 85, the other end of which bears 
against sleeve 86 which is threadably received in tapped bore 87 of end 
wall 80. Sleeve 86 has a bore 90 therein in line with hexagonal socket 89. 
A screwdriver slot 91 is provided in the end of sleeve 86 for receiving a 
screwdriver for turning sleeve 86 to adjust the force on spring 85. 
Screwdriver slot 91 consists of two diametrically aligned slots spaced 
180.degree. from each other on sleeve 86. 
In FIG. 9 the check valve structure of shock absorber 10c is set up to 
cause it to operate in compression, that is, when the piston moves in the 
direction of arrow 92. However, if it is desired to cause the shock 
absorber to operate in tension, that is, when the piston moves in the 
direction of arrow 93, it is not necessary to remove end wall 80, as in 
the embodiments of FIGS. 7 and 8. All that is required is to unscrew 
sleeve 86 by applying a screwdriver to slot 91, remove spring 85 and check 
valve 84, reinsert the spring 85 so that one end bears against seat 82, 
reinsert check valve 84, and thereafter thread sleeve 86 into position so 
that the ball check valve 84 will bear against seat 94 on sleeve 86. The 
axial position of sleeve 86 will determine the force of spring 85 on ball 
84. The embodiment of FIGS. 9 and 10 is basically similar to the 
embodiments of FIGS. 1-3 except that the end wall 80 is press-fitted in 
position and utilizes a ball check valve. 
It can thus be seen that the improved shock absorber device of the present 
invention is manifestly capable of achieving the above enumerated objects, 
and while preferred embodiments of the present invention have been 
disclosed, it will be appreciated that it is not limited thereto but may 
be otherwise embodied within the scope of the following claims.