Shock absorber spring adjuster

A shock absorber assembly includes a piston/tube shock mechanism provided with adjustment devices permitting variation of the effective length and thus operating parameters, of a coil spring surrounding the shock mechanism. Adjustment is obtained by the vertical displacement of a member surrounding a body sleeve disposed exteriorly of the shock mechanism and wherein this vertical displacement alters the elevation of one end of the coil spring. A lock nut secures the obtained adjustment and both the member and nut may be manipulated with a simple tool cooperating with a specific configuration on the periphery of the member and nut.

REFERENCE TO CROSS-RELATED APPLICATION 
This application discloses subject matter that was disclosed in application 
Ser. No. 07/265,554, filed Nov. 1, 1988, abandoned. 
FIELD OF THE INVENTION 
This invention relates generally to an improved shock absorber assembly and 
more particularly, to a shock absorber provided with an adjustment 
mechanism permitting simple and rapid alteration of the effective length 
of the coil spring concentrically disposed about the telescoping shock 
absorber components. 
BACKGROUND OF THE INVENTION 
Many vehicles use a suspension system consisting of coil springs 
concentrically mounted over telescoping tubular shock absorbers. An 
example is the MacPherson suspension system commonly used on many models 
of small cars. This system has also become a popular modification for 
other systems, especially in off road vehicles and/or four wheel drive 
vehicles. From time to time it is desirable, if not necessary, to adjust 
the compression rate or effective length of the springs in such assemblies 
for a number of possible reasons, including weakening of the springs over 
a prolonged period of time, heavy or uneven loads carried in the vehicle, 
and changing road or terrain conditions. 
DESCRIPTION OF THE RELATED ART 
Adjustable shock absorbers have typically utilized collars secured with set 
screws and locked into the shock absorber body, or clamps surrounding the 
body. Such examples will be found in Stresnak et al U.S. Pat. No. 
3,010,714 of Nov. 28, 1961, Schmidt U.S. Pat. No. 3,043,581 of July 10, 
1962, and Osterhoudt U.S. Pat. No. 3,096,084 of July 2, 1963. The forces 
necessary to secure these collars or clamps to preclude their movement 
along the shock absorber body under conditions of very high spring 
compression, such as occurs when a heavily loaded vehicle rapidly 
traverses uneven terrain, may be sufficient to distort the shock absorber 
body to the extent that the shock absorber is damaged and/or no longer 
operable. Additionally, such devices fail to offer a simple manner of 
obtaining a precise or minute re-adjustment. 
Although devices as described above are adjustable, the nature of their 
attachment to the smooth shock absorber body requires that in order to 
perform such an adjustment the concentric surrounding spring must be 
compressed by means of special tools not normally found outside of vehicle 
maintenance and repair shops. The forces contained by these tools while 
holding such a spring in compression may also create some hazard should 
one or more of the spring compression tools slip. 
Benya et al U.S. Pat. No. 4,366,969 of Jan. 4, 1983 seeks to overcome the 
problem of potential slippage by welding the collar to the shock absorber 
body. This can only be done during the manufacture of the shock absorber, 
as such a weld could not be successfully accomplished in the field or in a 
repair shop. The heat from such a weld would in all likelihood distort the 
shock absorber body, thereby rendering it inoperable. Performing a welding 
operation on a prefabricated shock absorber would also damage other 
internal components, such as elastomer seals of various types and 
hydraulic fluid, as well as the metals used in the construction of the 
shock absorber, by locally altering the heat treatment of such metals. 
By using a finite number of fixed steps or notches for adjustment in 
combination with a rotating collar, the above Benya et al patent does 
eliminate the need for spring compression tools for adjustment. In doing 
so, however, yet another problem is created, since such a collar 
arrangement is by its nature limited both in terms of the total length of 
adjustment available as well as the relatively small number of individual, 
finite adjustments available. 
SUMMARY OF THE INVENTION 
By the present invention, an improved apparatus for providing selective 
adjustment of the length and compression of coil springs mounted 
concentrically about telescoping tubular shock absorbers is disclosed. 
Accordingly, one of the objects of the present invention is to provide an 
improved device for quickly and simply adjusting coil springs arranged in 
the above manner on various vehicles or devices where such a system is 
used. 
Another object of the present invention is to provide a means of adjustment 
which is adjustable over a relatively wide range. 
Still another object of the present invention is to provide an infinitely 
variable means of adjustment. 
Yet another object of the present invention is to provide a means of 
adjustment which eliminates the need for spring compression tools. 
A further object of the present invention is to provide a device which 
cannot slip out of adjustment under conditions of extreme loading. 
Another object of the present invention is to provide a device which may be 
retrofitted to a standard production, readily available telescoping tube 
type shock absorber. 
An additional object of the present invention is to provide a means of 
adjustment which may be performed while the spring and shock absorber are 
under load and thus which does not require removal of the load prior to 
accomplishing the adjustment. 
With these and other objects in view which will more readily appear as the 
nature of the invention is better understood, the invention consists in 
the novel construction, combination and arrangement of parts hereinafter 
more fully described, illustrated and claimed, with reference being made 
to the attached drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, particularly FIG. 1, the present invention 
will be seen to comprise a shock absorber assembly, generally designated 
10, and which includes the usual shock sub-assembly 12 having a piston rod 
14 cooperating with a shock cylinder or tube 16. The details of the 
internal construction of the sub-assembly 12 will be understood to form no 
part of the present invention since, any one of various well known 
sub-assemblies may be utilized in combination with the mechanism providing 
the adjustability according to the present invention. Cooperating with the 
shock mechanism 12 is the well known compression spring 18 comprising a 
unitary steel member providing a plurality of coils 20 terminating 
respectively, in an upper end 22 and lower end 24. This spring 18 is 
concentrically disposed about the shock sub-assembly 12 with its upper end 
22 suitably retained against longitudinal displacement by means of an 
abutment member comprising an upper spring retainer clip 26. This clip 
includes a circular plate provided with a radial slot 28 adapted to 
receive the piston rod 14 and will be understood to be constantly urged by 
the spring against the stop presented by a knuckle or piston rod end 30 
the latter of which provides the top attachment means for the shock 
absorber assembly 10. The top surface 32 of the retainer clip 26 is 
preferably planar to present a smooth engagement with the rod end 30 while 
the lower surface of the clip will be seen to include a depending bottom 
section 34 of less diameter and forming a peripheral, circular recess 36 
within which the spring upper end 22 is seated. To provided the 
adjustability of the present invention, means are included to alter the 
height or effective length of the spring 18. This is accomplished by the 
selective manipulation of displaceable spring abutment means constantly 
engageable with the spring lower end 24. This means will be seen to 
comprise an end or adjustment sub-assembly 38 including a cylindrical body 
sleeve 40 concentrically disposed about the shock tube 16 and having 
external threads 42 thereon. 
The lower end of the shock absorber tube 16 projects from the bottom of the 
sleeve 40 and is affixed to the associated vehicle in the conventional 
manner, along with two laterally spaced apart flanges 44--44 depending 
from the bottom section 46 of the sleeve. This bottom section will be 
understood to be void of the threads 42 and thus serves as a bottom stop 
for the about to be described adjustment components carried by the sleeve 
threads 42. 
As will be seen most clearly in FIG. 1 of the drawing, an adjusting nut 48 
and adjacent lock nut 50 are concentrically mounted about the body sleeve 
40, with the adjusting nut being uppermost. Both are ring members provided 
with internal threads 52 mating with the threads 42 on the body sleeve 40. 
Although continuous threads are shown in the drawing, quite obviously 
suitable alternative interfitting means may be utilized to allow for the 
vertical displacement of the nut and lock nut. The uppermost adjusting nut 
48 includes an upper section 54 having a circular periphery defining a 
diameter which is slightly less that that of the spring coils 20 while an 
integral lower section 56 extends outwardly therefrom to offer a diameter 
no less than that of the spring coils and to provide an upwardly facing 
shoulder 58 upon which the spring lower end 24 constantly bears. The above 
mentioned lock nut 50, which may be of the same outer diameter as that of 
the adjusting nut lower section 56, includes suitable tool-receiving means 
such as notches 60 on its periphery, as does also the periphery of the 
adjusting nut lower section 56. With circular periheries on the nut and 
lock nut, the above mentioned notches 60 readily accept a simple tool such 
as a spanner wrench. Alternatively, flats (not shown) may be formed on the 
nut and lock nut peripheries to accept adjustable or slip-joint pliers or 
the like. The operation of the adjustment mechanism may now be related, 
with an understanding of the above described construction. The shock 
absorber assembly 10 as illustrated in FIG. 1 represents the relationship 
of the various components as they appear when the minimum compressive 
force of the spring 18 is in effect. This follows since the adjustment nut 
48 and lock nut 50 are located in their lower most position, in abutment 
with the body sleeve bottom section 46. To increase the applicable force 
of the spring 18, its effective length must be fore-shortened and this is 
obtained by using an appropriate tool, such as a spanner wrench (not 
shown) about the periphery of the adjusting nut 48. In this manner, as the 
threaded nut 48 is angularly displaced, it is vertically advanced along 
the threads 42 of the body sleeve 40, thereby progressively further 
compressing the spring as the coils 20 thereof are moved closer to one 
another. After the nut 48 has been shifted to the desired position, the 
lower most lock nut 50 is similarly moved upwards into engagement with the 
adjusting nut 48. The same tool may be used for this latter displacement 
or, alternatively, the lock nut may be initially shifted by hand and 
thence snugged, in a jam fashion, against the adjusting nut by means of 
the tool. Accordingly, it will be appreciated that the lock nut serves to 
retain the adjusting nut in its current position so that as the shock 
absorber assembly 10 is subsequently used in a vehicle, the vibrations, 
etc. will not alter the preset adjustment position. The combination of 
constant spring pressure on the adjusting nut and the forceful jamming of 
the lock nut thereagainst insure the stability of the mechanism. 
To preclude damaging frictional contact as well as to dampen noise and 
prevent entry of foreign material during operation of the present assembly 
10, sealing means such as an O-ring seal 62, is provided on the interior 
of the body sleeve 40, preferably adjacent its top edge 64. Quite 
obviously, alternate sealing means, such as a coating of suitable 
material, may be applied to the sleeve interior surface. 
From the foregoing description it will be appreciated that an improved 
shock absorber assembly has been presented and which offers an extremely 
simple, yet effective manner for the quick and positive adjustment of the 
spring member in order to vary its effective length in accordance with the 
parameters to be encountered during use of the associated vehicle. 
It is to be understood that the present invention is not limited to the 
sole embodiment described above, but encompasses any and all embodiments 
within the scope of the appended claims.