Abstract:
A device for locking a piston rod of a hydraulic piston and cylinder assembly in an extended condition. The locking device is placed in interposed relation to a hydraulic cylinder and an opposing bearing point to prevent retraction of the piston rod. The device has a split sleeve configuration to facilitate mounting the locking device in encircling relating to the piston rod including opposed longitudinally extending edges that are locked to one another via a locking means. The locking means of the device is partially enclosed by a lock protecting housing to protect the locking device from being removed by unauthorized persons. The device is durable, easy to install and remove, and adaptable to a variety of hydraulic piston and cylinder assemblies.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates, generally, to locking devices and more particularly to means for locking a hydraulic piston rod in an extended condition. 
     2. Description of the Prior Art 
     Heavy machinery such as bulldozers and backhoes often remain on the job site throughout the course of a construction project because the effort to transport the equipment to a secure site is expensive and time-consuming. The heavy machinery may be left on a job site for several days. The machinery is relatively unlocked and susceptible to theft and vandalism. 
     Buckets, blades and like attachments of heavy machinery operate using hydraulic cylinder and piston rod assemblies. The piston rod is retracted and extended from the cylinder using hydraulic pressure. During maintenance, a steel sleeve is commonly interposed between the connection point, or bearing, of the rod and the cylinder opening encircling the exposed piston rod. This supports the rod in an extended position so that in the event of loss of hydraulic pressure the rod will not uncontrollably retract within the cylinder thereby preventing undesirable movement of the attachment. 
     A sleeve can also be used as a locking device. The locking sleeve is similarly placed over the exposed piston rod as in maintenance use but the sleeve is also locked into place using a padlock. This will prevent the sleeve from being removed and thus secure the rod in an extended condition. With the rod in an extended position the attachments can be fixed in either a lowered or raised position making the unauthorized movement of the heavy machinery more difficult. 
     Prior art hydraulic locking devices include U.S. Pat. No. 4,373,851 to Confoey that describes a split cylindrical sleeve that encloses around the piston rod and includes extended tabs that are locked together using a padlock to prevent removal. The Confoey configuration is susceptible to having the padlock cut off using bolt cutters or broken off using extreme force. It would be desirable if a more secure locking system could be provided to protect against theft and vandalism. 
     In summary, the needed improvements include a locking device that is easy to install and remove which is also durable and protects against theft and vandalism. 
     However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled. 
     SUMMARY OF INVENTION 
     The long standing but heretofore unfulfilled need for a locking device for heavy machinery that can be used at unsecured construction sites or storage areas, which can be installed and removed easily, and which is durable, is now provided in the form of a new, useful and non-obvious device. 
     The novel structure includes a substantially rigid sleeve consisting of a pair of sleeve halves having diametrically opposite longitudinally extending meeting edges wherein said sleeve halves are hingedly connected along a first meeting edge via a hinge means so that said sleeve halves are openable for mounting on an extended piston rod. A locking means is disposed between said sleeve halves at a second opposing longitudinal extending meeting edge for releasably securing said sleeve halves to one another wherein said sleeve is adapted to fit snugly around said piston rod in encircling relation thereto. A half circle portion of an annular flange is disposed on a first end of each of said sleeve halves wherein the diameter of said annular flange is greater than the diameter of a cylinder of said hydraulic cylinder and piston assembly. A half portion of a lock protecting housing is disposed adjacently and in mirrored relation on each of said pair of sleeve halves so that a locking means can be enclosed therein when said sleeve is mounted on said piston rod. An apertured lug extends from and is secured to each of said sleeve halves within said lock protecting housing wherein each said lug is apertured for receiving a locking pin therethrough and said locking pin is releasably secured using said key. An overlying reinforcing band is disposed proximate to a second end of each of said sleeve halves so that stress loads concentrated at said second end are dissipated. 
     In a preferred embodiment, a commercially available shackleless locking means with a hidden pin assembly secures the sleeve halves to one another. 
     In a second embodiment, the locking device includes a standard sleeve half that is secured over the extended piston rod with a pin and bracket assembly. The pin and bracket assembly is placed between the transversely spaced first wall and second wall of the sleeve half member so that the extended rod is interposed between the channel-shaped member and the pin and bracket assembly. A similar shackleless locking means as in the first embodiment secures one end of the bracket within the lock so that the pin and bracket assembly cannot be removed from the sleeve half member thereby preventing removal of the sleeve from the extended piston rod. 
     An important object of the present invention is to provide an improved locking device, for use with heavy machinery that prevents the movement of a hydraulic piston rod and prevents the theft of the machinery. 
     Another object is to provide a means for attaching the locking device in its proper, functional location without undue effort so that the locking device may be easily installed and removed as needed. 
     Another object is to provide a locking device suitable for several different heavy machines without modification and which is durable and can withstand unauthorized removal attempts. 
     These and other important objects, advantages, and features of the invention will become clear as this description proceeds. 
     It is to be understood that both the foregoing general description and the following detailed description are explanatory and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate embodiments of the present invention and together with the general description, serve to explain principles of the present invention. 
     The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a first embodiment of the locking device of the present invention in a closed position; 
     FIG. 2 is a top view of a first embodiment of the locking device of the present invention in a closed position; 
     FIG. 3 is top view of the first embodiment in an open position; 
     FIG. 4 is a detailed view of the cylindrical housing and locking means of the first embodiment; 
     FIG. 5 is a side elevation of a backhoe equipped tractor and illustrating the first embodiment of the device; 
     FIG. 6 is a side elevation of a portion of a bulldozer illustrating the first embodiment of the device; 
     FIG. 7 is a cross sectional view of a piston rod and sleeve half illustrating the second embodiment of the device; 
     FIG. 8 is an exploded side view of the second embodiment; 
     FIG. 9 is a top view of the novel bracket of the second embodiment; and 
     FIG. 10 is front view of the novel bracket of the second embodiment. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIGS. 1 and 2, it will there be seen that the reference numeral  10  denotes a first embodiment of the novel locking device as a whole. Device  10  will be known commercially as the SleevLock™. 
     In this first embodiment, locking device  10  includes a first sleeve half  20  and a second sleeve half  30  each having a channel shape with a longitudinally disposed hinge  100  therebetween. Half circle portions  60  and  70  are disposed on a first end of each of the sleeve halves  20  and  30 , respectively, forming an annular flange of a diameter greater than the diameter of a hydraulic cylinder housing of heavy machinery. Reinforcing bands  80  and  90  are attached proximate to a second end of each sleeve half,  30  and  20  respectively, thereby providing additional structural strength for supporting high stress loads concentrated at the interface between locking means  10  and the bearing point. An annular housing for protecting a locking means is disposed opposite said hinge  100  as seen in FIGS. 1 and 2 of the drawings and denoted  40  and  45 . An apertured lug  50  extends from and is secured to each of said sleeve halves  20  and  30  within the cylindrical housing. Lug  50  is apertured for placement of a locking means therethrough. Half cylindrical portions  40  and  45  form said annular housing wherein each of said two cylindrical halves  40  and  45  partially enclose said locking means therein when the sleeve  10  is in the closed position. 
     Referring now to FIG. 3 of the drawings, sleeve halves  20  and  30  are pivotally connected along first opposing longitudinally extending meeting edges by hinge  100 . Hinge  100  comprises several offset extensions  105  from each of said sleeve halves  20  and  30  that are alternatively integrated with a longitudinal hinge pin (not shown) positioned through an aperture in each of said extensions. A resilient pad  110  is disposed on the interior surface and proximate to both ends of each sleeve halves  20  and  30  to protect machinery from damage and to provide a more secure fit of the locking device  10  when in a closed position. 
     In FIG. 4 of the drawings, locking means  120  secures the longitudinal extending meeting edges to one another via apertured lug  50 . In the preferred embodiment, locking means  120  is a commercially available shackleless lock that includes a hardened steel cylindrical shell with a retractable locking pin that is only accessible from a lower side of locking means  120 . Locking means  120  is lowered over lugs  50  within the cylindrical housing wherein locking means  120  includes a slotted recess on a lower side for receiving said lug  50 . Lug  50  is slidingly received within the recess of locking means  120  wherein the cylindrical housing partially encloses the locking means wherein only the solid upper side of the locking means is exposed. The retractable locking pin is then manipulated to slide through the aperture of lug  50  using a unique key (not shown) and then locked into place using said key. The locking pin and lug are practically inaccessible to any unauthorized person. The locking means cannot be removed efficiently without the key. 
     Locking device  10  is shown in FIG. 5 of the drawings installed on a tractor  130  with a typical backhoe attachment  180 . Backhoe attachment  180  includes a pair of booms  140  and  160  and a bucket  190  pivotally attached to one another. Boom  140  operates via corresponding hydraulic piston and cylinder assembly  150 . Piston rod  200  of first boom  160  is shown in an extended position and device  10  is shown in a closed and locked position encircling rod  200 . Annular flange ( 60  and  70 ) is in abutting relation to cylinder  150  and has a diameter greater than cylinder  150  wherein the opposing end of locking device  10  abuts boom  140 . Thus, any hydraulic force generated by an attempt to retract the piston rod  200  within cylinder  150  when device  10  is installed is distributed to the outer cylinder wall thus decreasing the potential for damage to the mechanical capabilities of attachment  180  during a theft or vandalism attempt. It will thus be seen that with locking device  10  in place, boom  140  and bucket  190  cannot be raised from the ground and thereby prevents the tractor from being moved. A second locking device can be installed on hydraulic piston and cylinder assembly  170  if desired for additional security protection. However, placing locking device  10  solely on second piston rod  202  would not provide the desired security protection to prevent bucket  190  from being raised. 
     In FIG. 6 of the drawings, a portion of a bulldozer  205  is shown having a blade attachment  210 . Blade  210  is pivotally attached to bulldozer  205  and operates via a hydraulic piston and cylinder assembly  220 . Piston rod  230  of cylinder  220  is in an extended position and device  10  is shown in a closed and locked position encircling rod  230 . Annular flange ( 60  and  70 ) is in abutting relation to cylinder  220  and has a diameter greater than cylinder  220  wherein the opposing end of locking device  10  abuts blade  210 . Similar to backhoe attachment  180  shown in FIG. 5, any hydraulic force generated by an attempt to retract the piston rod  230  within cylinder  220  is distributed to the outer cylinder wall thus decreasing the potential for damage to the mechanical capabilities of blade  210  during a theft or vandalism attempt. It will thus be seen that with locking device  10  in place, blade  210  cannot be raised from the ground and thereby prevents bulldozer  205  from being moved. 
     Referring now to FIG. 7, a second embodiment of the locking device is illustrated by sleeve half  300  mounted and partially encircling piston rod  330 . Bolt  320  passes through a pair of apertures disposed on the transversely spaced sidewalls of sleeve  330  and through a pair of aligned apertures located on bracket  310 . Head  325  of bolt  320  has a diameter greater than aperture diameters of bracket  310  thus securing bolt  320  within the apertures. Locking means  120  is identical to the locking means of the above described first embodiment. The inner side of lock  120  has a recess  327  that allows the projecting flange of bracket  310  to be inserted therein. An aperture located in the top flange of bracket  310  allows locking pin  125  to be placed therethrough. A key.(not shown) secures locking pin  125  into a locked position so that bracket  310  cannot be removed from lock  120 , thus preventing bracket  310  from being removed from sleeve  300 . With bracket  310  securely in place, bolt  320  cannot be removed from bracket  310  thereby preventing sleeve  300  from being removed by unauthorized means from around piston rod  330 . Sleeve  300  is mounted in similar fashion as the first embodiment with a first end in abutting relation to a hydraulic cylinder wherein the opposing end of sleeve  300  abuts a bearing point. The novel bracket  310  and bolt  320  assembly used in conjunction with locking means  120  is suitable to be used with standard sleeves known in the industry as safety devices commonly used during maintenance procedures and the like. 
     In FIG. 8, locking means  120  is shown with locking pin  125  withdrawn. Recess  327  is shown without top flange of bracket  310  inserted. FIG. 9 is a top view of bracket  310  showing locking pin aperture  340 . Top aperture  340  provides the means to secure bracket  310  via locking pin  125  within locking means  120 . FIG. 10 is a front view of bracket  310  showing a first front aperture  350  thereby providing a means to place bolt  320  therethrough. A second aperture (not shown) is aligned and cooperates with front aperture  350  to secure bolt  320  on either side of a sidewall of sleeve  300 . 
     The locking device can be installed without undue effort and thus is easily installed and removed as desired. The locking device is durable and can withstand unauthorized removal attempts and is suitable for any heavy machine with a like hydraulic piston and cylinder assembly. Additionally, the locking device can be manufactured to any desired length or diameter to fit any piston and cylinder assembly that may be different in magnitude of size. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween. 
     Now that the invention has been described.