Abstract:
An improved hydraulic cylinder construction having a feature thereon facilitating operative connection with a service kit to enable a quick and injury free removal thereof from a location whereat the hydraulic cylinder is spring biased in a shock absorber installation, particularly for use in a scraper blade mounting assembly.

Description:
This application claims the benefit of Provisional Application No. 60/369,910 filed Apr. 4, 2002. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to an improved hydraulic cylinder construction and, more particularly, to a cylinder construction for use on a snow scraper blade mounting for trucks and a service kit therefor. 
     BACKGROUND OF THE INVENTION 
     This invention arose out of a need to minimize the down time involved in repairing a hydraulic cylinder mounted on a truck for use in controlling the elevation of a snow scraper blade. A typical hydraulic cylinder mounting is disclosed in U.S. Pat. No. 3 086 303. The subject matter of this patent is to be incorporated herein by reference. The difficulty in gaining access to the hydraulic cylinder after it, along with the spring housing, has been removed from the truck is to effect a compressing of the spring in order to facilitate removal of the nuts and bolts limiting the downward travel of the hydraulic cylinder within the spring housing. Since the spring is large and the spring force is also large, there is a risk of injury if the spring compression activity is not carefully controlled while the travel limiting nuts and bolts are removed. 
     Accordingly, it is an object of this invention to provide a hydraulic cylinder mounting assembly which can be easily assembled and disassembled from a truck as well as easily accessing the hydraulic cylinder to facilitate a repair thereto or replacement thereof. 
     It is a further object of the invention to provide a service kit for facilitating removal of the hydraulic cylinder from the spring housing. 
     It is a further object of the invention to provide a service kit, as aforesaid, wherein the force of the spring is overcome to enable the hydraulic cylinder to be removed from the spring housing. 
     It is a further object of the invention to provide a service kit, as aforesaid, which is easy to use and is not dangerous to the user while it is in use. 
     SUMMARY OF THE INVENTION 
     The objects and purposes of the invention are met by providing a hydraulic cylinder and a service kit therefor for facilitating removal of the hydraulic cylinder from the spring housing. The service kit is usable in association with a hydraulic cylinder having a cylinder housing, and an elongate piston rod reciprocal in the cylindrical housing and a spring abutment collar adjacent a first end from which projects the piston rod. The hydraulic cylinder is mounted in a spring housing which is open at opposite ends while simultaneously providing a spring abutment at a second and remote from a third end whereat the piston rod projects from the spring housing. A stop ring encircles the hydraulic cylinder adjacent the first end and is secured to the spring housing adjacent the third end. A spring is oriented in a compressed state between and engaging the spring abutment collar and the spring abutment to continually urge the cylinder housing and the spring abutment collar thereon toward the stop ring. The cylinder housing has a fluid connection at a fourth end remote from the first end. The hydraulic cylinder additionally includes an opening having a first internal thread therein. The service kit includes a coupling member having a first external thread at one end and an enlarged head at the other end. The first external thread is configured to threadedly couple directly to the first internal thread. The service kit also includes an abutment member which has a hole therethrough configured to loosely receive therethrough the first external thread but preventing the enlarged head from passing therethrough. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a highway truck with a snow scraper blade mounted in operative position thereon by means of mounting connections; 
     FIG. 2 is an enlarged side view of a conventional support mechanism for the spring housing; 
     FIG. 3 is a cross sectional view through the longitudinal center of the inventive hydraulic cylinder and spring housing mount therefor; 
     FIG. 4 is an exploded isometric view of the hydraulic cylinder and spring housing assembly; 
     FIG. 5 is a top of view of a fragment of the hydraulic cylinder housing adjacent the end from which the piston rod extends; 
     FIG. 6 is a side view of FIG. 5; and 
     FIG. 7 is a sectional view taken along the line  7 — 7  of FIG.  6 . 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates a conventional highway maintenance truck having a frame  1 , rear driving wheels  2  and front wheels  3  with the usual operator&#39;s cab  4  and bed  5 . An elongate snow scraper blade  6  having a wearing edge plate  7  is mounted obliquely across the underside of the frame  1  by means of a pair of upright mounting posts  8  and  9  secured to the side frame members by identical brackets  10 . The posts  8  and  9  rigidly support a hinge shaft  11  from which the scraper blade is pivotally supported by means of knuckle plates  12  secured to the back side of the blade a the upper edge thereof. 
     An adjusting cylinder support bracket  13  of a channel shaped cross section is provided with a sleeve  14  on its forward end supported upon the hinge shaft  11  so that the bracket projects perpendicularly to the hinge shaft and obliquely to the frame of the truck. Spaced rightwardly (FIG. 2) from the sleeve  14  the web of the channel bracket  13  defines a transverse slot  15  adjustably receiving a clamp screw  16  which clamps the lower end of a third cylindrical support post  17  to the bracket  13 . The post  17  projects upwardly and is fixedly secured in a third mounting bracket  18  secured to the side frame member  1  of the truck. The third mounting bracket  18  may be identical to the previously described brackets  10 . 
     Toward the rear end of the mounting bracket  13 , the side flanges  23  of the channel shaped bracket have upwardly and rearwardly inclined trunnion plates  24  secured thereto with inwardly projecting male trunnion bearings  25  near their upper ends. The bearings  25  coact with and pivotally support the female trunnion bearings  26  projecting transversely from a cylindrical spring housing  27 . The lower left end  28  of the spring housing  27  is open and is axially slotted as at  29  (FIG. 3) on its upper side. The upper right end  31  of the spring housing  27  defines a center hole  32  for a fluid connection surrounded by an annular spring abutment  33 . A short length of angle iron  34  is welded over the slot  29  to protect the slot and restore the strength of the cylinder housing  27 . 
     Centrally and reciprocally within the spring housing  27  is inner hydraulic cylinder  36  substantially smaller than the spring housing  27  and having an annular abutment  37  projecting outwardly adjacent its lower left end. An ear on the annular abutment  37  projects into the slot  29  to prevent rotation of the hydraulic cylinder while permitting axial movement of the hydraulic cylinder. A split ring stop  39  is received in the lower end  28  of the spring housing  27  and is secured thereto by a plurality of bolts  41  (FIG. 4) received in tapped holes  40 . A heavy compression spring  42  is positioned within the spring housing  27  and bears between the abutments  33  and  37 . 
     The hydraulic cylinder  36  includes a cylindrical body  43  having at its upper right end  44  a relatively thick end plate  46  (FIG. 3) closing off the upper end of the cylindrical body  43 . The end plate  46  has an internally threaded opening  47  extending therethrough. A bolt  48  having an enlarged head  49  at one end and an external thread  50  at the other upper right end configured so that the external thread  50  is threadedly received directly into the internally threaded opening  47 . A lock washer  45  can be provided if desired. The bolt  48  has a central passageway  51  therethrough with the upper right end of the passageway  51  located within the enlarged head of the bolt  48  being internally threaded as at  54  and configured to receive a fluid connection member  55  (FIG. 1) therein. 
     A piston to  52  is reciprocally mounted within the cylindrical body  43 . A cylinder rod  53  is fixedly secured to the piston  52  and is movable therewith. The distal end of the piston rod at  52  is configured to be secured to the snow scraper blade  6  in a conventional manner as depicted in FIG.  2 . 
     The cylindrical body  43  additionally has a fluid inlet port  59  adjacent the lower left end thereof The inlet port  59  is configured for connection to fluid supply as at  61  (FIG.  1 ). 
     In this particular embodiment, the ear  38  has a wear piece  57  fastened thereto by a screw  58 . The wear piece  57  is configured to slidably engage the angle iron  34  and protect the ear  38  from wear as well as assure alignment of the inlet port  59  with the slot  29 . 
     In order to disassemble the assembly illustrated in FIG. 3, a service kit  60  consisting of an elongate bolt  62  (FIG. 4) in combination with a disk or plate  63  is provided, the plate  63  having a central hole  64  therethrough the diameter of which is smaller than the enlarged head  66  on the bolt  62 . The external thread  67  on the bolt  62  is configured to directly threadedly engage the internally threaded opening  47 . First, however, the bolt  48  must be removed from the internally threaded opening  47 . This will also necessitate the removal of all of the fluid connection lines that are coupled to the hydraulic cylinder  36 . Thereafter, the bolt  62  is oriented so that the threaded end  67  thereof is inserted through the central hole  64  in the plate  63 . The threaded end  67  of the bolt  62  is then inserted into the internally threaded opening  47 . The length of the bolt  62  is sufficiently long that several turns thereof are required before the head end  66  engages the plate  63 . Once the head end  66  engages the plate  63 , continued rotation thereof is to occur and the end plate  46  will be drawn toward the plate  63  to compress the spring  42  and draw the annular spring abutment collar  37  away from the split ring  39 . Thereafter, the bolts  41  can be removed so that the split ring  39  can be removed from the spring housing  27 . An this time, the bolt  62  can be rotated in the opposite direction so that the end plate  46  and the hydraulic cylinder  36  are driven away from the plate  63  and the annular spring  33 . The bolt  62  is sufficiently long to facilitate a total relaxation of the spring  42  before the thread  67  thereof disengages from the thread  47 . After the bolt  62  has exited from the internally threaded opening  47 , the hydraulic cylinder  36  can be drawn out of the spring housing  27  at the left end of the spring housing  27  for replacement and/or servicing. 
     In order to install a repaired or new hydraulic cylinder  36  into the spring housing  27 , one need only reverse the procedure described above. 
     Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.