Abstract:
The power drive includes a housing enclosing a gearing system and a motor. The housing is mounted under the floor of a transport trailer. A drive shaft extends outside the housing for connection in series with a cross shaft of the landing gear of the trailer. A gear shift actuator is mounted in the gearing system for engagement or idling of the gearing system. The gear shift actuator comprises a rod that is movable in and out of the driver side of the housing. A handle lock saddle is mounted to the driver side of the housing for retaining a crank handle of the landing gear thereto. The saddle is centered on the rod such that the rod must be pushed inward for mounting the crank handle to the handle lock saddle. The gearing system is inoperable if the crank handle is not securely stowed to the handle lock saddle.

Description:
The present invention claims the benefit of U.S. Provisional Application No. 61/687,070, filed Apr. 18, 2012. 
     FIELD OF THE INVENTION 
     This invention pertains to landing gears for transport trailers, and more particularly it pertains to a retrofit power drive unit for mounting in series with the cross shaft of a landing gear system. 
     BACKGROUND OF THE INVENTION 
     Electric, pneumatic and hydraulic drives have been in use for many years to facilitate the operation of landing gears on transport trailers. The following documents provide a good inventory of auxiliary, non-manual drive systems that have been found in the prior art for operating landing gears on transport trailers.
     Canadian Patent 1,072,940 issued to Joseph P. Orth et al. on Mar. 4, 1980;   Canadian Patent 2,039,149 issued to R. P. Whittingham on Mar. 14, 1991;   Canadian Patent 2,339,156 issued to J. M. Alguera-Gallego et al. on Apr. 24, 2007;   Canadian Patent 2,531,272 issued to Frank J. Drake, on Mar. 16, 2010;   Canadian Patent Appl. 2,621,342 filed by Giancarlo Brun, on Aug. 14, 2006;   U.S. Pat. No. 2,875,980 issued to K. Grace on Mar. 3, 1959;   U.S. Pat. No. 3,077,120 issued to A. F. Viehweger, jr. on Feb. 12, 1963;   U.S. Pat. No. 3,189,322 issued to C. G. Hadek on Jun. 15, 1965;   U.S. Pat. No. 3,136,527 issued to L. Griffis on Jun. 9, 1964;   U.S. Pat. No. 3,341,179 issued to C. B. Smith on Sep. 12, 1967;   U.S. Pat. No. 4,097,840 issued to Warner A. Chappelle on Jun. 27, 1978;   U.S. Pat. No. 4,116,315 issued to Ervin K. Vandenberg on Sep. 26, 1978;   U.S. Pat. No. 4,129,322 issued to Martin Kuntz, Jr. on Dec. 12, 1978;   U.S. Pat. No. 4,281,852 issued to Raymond L. Konide on Aug. 4, 1981;   U.S. Pat. No. 4,466,637 issued to Carl A. Nelson on Aug. 21, 1984;   U.S. Pat. No. 5,299,829 issued to B. A. Rivers, Jr. et al., on Apr. 5, 1994;   U.S. Pat. No. 5,451,076 issued to Paul Burkhead on Sep. 19, 1995;   U.S. Pat. No. 6,224,103 issued to Edwin B. Hatcher on May 1, 2001;   U.S. Pat. No. 6,260,882 issued to Richard A. Kingsbury on Jul. 17, 2001;   U.S. Pat. No. 6,896,289 issued to Larry A. Gross on May 24, 2005;   U.S. Pat. No. 6,926,305 issued to Jeffrey Daniel on Aug. 9, 2005;   U.S. Pat. No. 7,163,207 issued to Darryl W. Baird et al. on Jan. 16, 2007;   U.S. Pat. No. 7,311,331 issued to Danny McGlothlin on Dec. 25, 2007;   U.S. Pat. No. 7,429,061 issued to John T. Perkins on Sep. 30, 2008.   

     Although all the power drive systems of the prior art deserve undeniable merits, these systems are not easily deactivated for use of a conventional hand crank in case of a malfunction of the power drive. In many installations in the prior art, the hand crank is no longer needed and is often stowed away and lost. It is believed that there is a need in the trucking industry for a better power drive system that is reliable, safe to operate, and that can be easily converted back to a manual operation when the need occurs. 
     SUMMARY OF THE INVENTION 
     In the power drive for landing gear according to the present invention, there is provided; a housing that can be mounted to the floor frame of a transport trailer; a gearing system mounted in that housing and a drive shaft that is included in that gearing system. The drive shaft extends in opposite directions from the housing for connection in series with a cross shaft of the landing gear. The gearing system is operable by an electric motor, although an hydraulic or a pneumatic motor may also be used. 
     There is also provided a gear shift actuator mounted in the gearing system for engagement of, or for idling the gearing system. The gear shift actuator comprises a rod that protrudes from the housing through the driver side of the housing. This rod is movable in and out of the driver side of the housing. A handle lock saddle is mounted to the driver side of the housing for retaining a crank handle of the landing gear thereto. The lock saddle is centered on the aforesaid protruding rod such that the rod must be pushed inward the driver side of the housing for mounting the crank handle to the handle lock saddle. The gearing system is inoperable if the crank handle is not securely stowed to the handle lock saddle. 
     On the other hand, when the crank handle is taken out of the handle lock saddle, the gear shift actuator is urged outwardly, causing the idling of the gearing system. The landing gear system can then be operated manually as if the power drive was not present. 
     In yet another aspect of the present invention, the controls of the landing gear system include switches to prevent the operation of the power drive if the truck is not connected to the trailer or if the cover portion of the housing is not properly mounted in place. 
     This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of the present invention is illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which: 
         FIG. 1  is a partial cross-section view of a flat bed trailer, showing a preferred installation of the power drive system according to a preferred embodiment of the present invention; 
         FIG. 2  is a driver side view of the housing of the power drive with a manual crank handle affixed to it; 
         FIG. 3  is another driver side view of the housing of the power drive with the crank handle removed, and showing a cutaway view inside the housing; 
         FIG. 4  is a front end view of the housing of the power drive showing another cutaway view inside the housing; 
         FIG. 5  is a logic diagram of the first preferred control circuit that can be used to operate the preferred power drive; 
         FIG. 6  is a wiring diagram of a second preferred control circuit that can be used to operate the preferred power drive; 
         FIG. 7  illustrates an alternate preferred arrangement of a leg displacement monitoring device mounted inside the housing of the preferred power drive. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , the power drive  20  according to the preferred embodiment of the present invention is mounted in series with the cross shaft  22  of the landing gear  24 . The landing gear  24  that is of interest herein is the type that has telescoping legs, a screw jack (not shown) in each leg and a right-angle pinion gear set (not shown) in the upper end of each leg. These pinion gear sets are connected to the cross shaft  22  for simultaneous extension or retraction of the legs by rotation of the cross shaft. 
     During installation of the power drive  20 , the existing cross shaft  22  is cut and a central segment is removed. The power drive  20  is fitted to the cross shaft  22  with appropriate couplings  28 . For that purpose, the power drive  20  has a drive shaft  30  that is protruding from each side of the housing for connection to the couplings  28  and to the cross shaft  22 . The couplings  28  are selected with proper size and torque rating so that the modified cross shaft  22  has a same or better strength than the original cross shaft. 
     The housing  32  of the power drive  20  has four suspension bolts  34  extending on its upper surface. The floor frame of the trailer is fitted with spaced-apart angle irons  36  with slots (not shown) to receive the suspension bolts  34 , and to retain the housing  32  to the floor frame of the trailer and to retain the drive shafts  30  of the power drive  20  in alignment with the cross shaft  22 . 
     The driver side of the housing  32  has a handle lock saddle  40  mounted thereto. A gear shift actuator rod  42  protrudes through the housing  32  at a mid point in the handle lock saddle  40 . The gearing system of the power drive  20  is engaged only when the crank handle  44  of the landing gear is stowed and retained to the handle lock saddle  40 . The stowing of the crank handle  44  causes the gear shift actuator rod  42  to be pushed in all the way through the lock saddle  40 . The operation of the gear shift actuator  42  will be better understood when looking at  FIGS. 3 and 4 . 
     In  FIG. 2 , the crank handle  44  is shown as being mounted into the handle lock saddle  40 . The handle lock saddle  40  has a cylindrical shape that is made of two curved receiving halves  40 ′. The curved receiving halves  40 ′ have concave surfaces facing outwardly from the driver side of the housing. The two curved receiving halves  40 ′ are separated by a curved covering piece  40 ″ that is hinged to the two receiving halves  40 ′. The covering piece  40 ″ has a concave surface facing inward toward the driver side of the housing. The covering piece  40 ″ is movable between the two receiving halves  40 ′ to lie in a coaxial alignment with the two receiving halves  40 ′. When the central covering piece  40 ″ is swung inward, it forms with the curved receiving halves  40 ′ a cylindrical cavity that is a close fit over the shank of the crank handle  44 , for firmly retaining this handle  44  into the lock saddle  40 . A first eccentric latch  46  is used to retain the central covering piece  40 ″ in a locked position enclosing the handle  44  into the lock saddle  40 . It will be appreciated that although an eccentric latch is illustrated, other latch systems can also be used. 
     Also in  FIGS. 2 ,  3 ,  4  a D-ring anchor  48  can be seen. This D-ring anchor  48  is mounted next to handle lock saddle  40  and it is used for retaining the grip end of the crank handle  44  to the housing  32 , as may be understood from  FIG. 2 . Referring now to  FIGS. 3 and 4 , the handle lock saddle  40  is illustrated in the open position. As mentioned herein before, the gear shift actuator rod  42  protrudes through the driver side wall of the housing  32  at the center of the handle lock saddle  40 . 
     The gear shift actuator rod  42  is an extension of a gear shift shaft  60  on which is mounted an intermediate gear  62 . This intermediate gear  62  is movable along the axis of the gear shift shaft  60  to engage with a driven gear  64  on the drive shaft  30  and a drive gear  66  on an electric motor  68 . It will be appreciated that the gearing system inside the power drive  20  may be more elaborate than illustrated. The intermediate gear  62  is movable along the axis of shaft  60  and it is normally urged away from an engagement with the drive and driven gears  64 ,  66  by a spring  70 . 
     As it will be understood, the gear shift actuator rod  42  must be pushed inward to mount the crank handle  44  into the handle lock saddle  40 , thereby causing the intermediate gear  62  to engage with both the drive gear  66  and the driven gear  64 . For more safety, a limit switch  72  is mounted inside the housing  32  and it is connected to the control circuit of the power drive, which will be described later, to monitor the position of the intermediate gear  62 . 
     The engagement of the intermediate gear  62  and the electric operation of the power drive  20  is only possible when the crank handle  44  is stowed away in the handle lock saddle  40  and the gear shift actuator rod  42  is held inward all the way. 
     It will be appreciated that the drawing in  FIG. 4  has been simplified for clarity. The mechanism to connect the movement of the push rod  42  and the spring  70  to the intermediate gear  62  can be designed in many other arrangements. For example, the movement of the push rod  42  can be used to actuate a fork-type lever as in automotive transmissions. The movement of the push rod  42  can be dampened by an axial damper if the gears do not mesh easily together. The movement of the push rod  42  can also be monitored by a switch, and that switch can be used to energize an electric clutch on the intermediate gear  62  in another example. Therefore, the illustration and description of the mechanism in the preferred embodiment should not be limiting the structure of the power drive of the present invention. 
     Referring back to  FIGS. 1 ,  2 , and  3 , the housing  32  is made of two portions  80 ,  80 ′ that are removable to expose the gearing system and the circuit box inside the housing  32 . The removable cover portions  80 ,  80 ′ are held to the housing  32  by a pair of eccentric clamps  82 , one on each side of the housing  32 . A second limit switch  84  is positioned inside the housing against one of the removable cover portions  80  and it is connected to the aforesaid control circuit to ensure that the cover portions  80 ,  80 ′ are in held tightly together before operating the power drive  20 . 
     As seen in  FIGS. 1 and 2 , a control pendant  86  is provided to operate the control circuit of the power drive from a remote location. The logic diagram for the first preferred control circuit is illustrated in  FIG. 5 . 
     The first preferred control circuit of the power drive contains two portions which are both enclosed inside the housing  32 . The top portion in the diagram of  FIG. 5  contains a 12 volt power cable  90  from the trailer&#39;s electrical system; a 10 amp. fuse, an “ON” relay switch R 1  and a battery charger. The second circuit portion contains a 12 V battery, a 150 amp. circuit breaker and a 100 amp. bimetallic type circuit breaker controlling a pair of solenoid switches S 1  and S 2   b . The electric motor  68  is operated forward and reverse, (up and down) by the pair of solenoid switches S 1  and S 2 . Push buttons UP and DWN on the pendant  86  are protected by a 10 amp. fuse, and are enabled by the “ON” relay switch R 1 , and by the limit switches SW 1 - 72  and SW 2 - 84  which were described earlier. Limit switches SW 1  and SW 2  are preferably moisture-resistant magnetic type switches. Another keylock switch may be incorporated in the pendant  86  for convenience. 
     A first pilot light Lt 1  on the driver side of the housing  32  indicates that the power drive  20  is connected to a source of electrical power. A series of limit switches SW 3 , SW 4 , SW 5 , SW 6  are provided in or on the legs of the landing gear and additional visual indicators Lt 2 , Lt 3 , Lt 4 , Lt 5  are also provided on the driver side of the housing  32  to indicate the “legs fully up” position and “legs fully down” position Limit switches SW 3 , SW 4 , SW 5 , SW 6  are also preferably moisture-resistant magnetic type switches. 
     A pair of encoders E are also included, one in each leg of the landing gear, to monitor an even raising or an even descending of the legs of the landing gear. The encoders E are connected to a programmable logic controller PLC and to a light Lt 6 . The light Lt 6  indicates an improper operation of the legs, either by a broken cross shaft  22 , a damaged coupling  28  or other failure or malfunction of that nature. 
     An alternate control circuit for operating the power drive is illustrated in  FIG. 6 . This alternate circuit is preferably included in a printed circuit board that is enclosed inside the housing  32 . Again, a schematic illustration of this alternate circuit is illustrated in  FIG. 6  to facilitate the understanding of the operation thereof. The actual circuit to be used in a commercial version thereof may contain many more components. 
     The second preferred circuit contains a battery charger, including a voltage and amperage regulator R, and a pair of relays controlling the forward and reverse rotations of the motor  68 . These relays are referred to on the drawing as the up and down relays. 
     This second preferred circuit is different from the first one illustrated in  FIG. 5 , basically, in the fact that the limit switches SW 3 , SW 4 , SW 5 , and SW 6  for the legs up or down signals have been eliminated. In the second preferred circuit, the monitoring of the leg movements is effected by a leg displacement monitoring device which is partly illustrated in  FIG. 7 . The leg movement monitoring device is made of a threaded sleeve  92  that is affixed over to the drive shaft  30 , for rotation with the drive shaft. A threaded follower block  94  is mounted to the threaded sleeve  92  for movement along the threaded sleeve  92 . The follower block  94  is guided against a guide rail  96  for movement along the drive shaft  30 . When the drive shaft  30  rotates, the follower block  94  moves sideways a displacement that is proportional to the extent of extension or retraction of the legs of the landing gear. The follower block  94  has a pair of magnets  98  thereon. The end-of-travel limits of the follower block  98  are monitored by a pair of magnetic switches MS 7  and MS 8 . 
     The magnetic switches MS 7  and MS 8  are located along the guide rail  100  and are spaced apart a distance that corresponds to the limits of the legs up and legs down movements. These switches are connected to the printed circuit board in a “normally closed” NC state in order to de-energize the electric motor M at the limits of the leg displacements. 
     It will be appreciated that the features in one preferred circuit can be used in the other one. For example, the leg displacement monitoring device as partly illustrated in  FIG. 7  can be used with the first preferred circuit illustrated in  FIG. 5 , and the encoders on the legs of the landing gear can be used with the circuit board as illustrated in  FIG. 6 . Also, the safety relay R 1  in the first preferred diagram, or the pendant  86  can also be incorporated in the circuit shown in  FIG. 6 . 
     As to other details and manner of operation of the power drive according to the present invention, the same should be apparent from the above description and drawings, and accordingly further discussion related to these aspects is deemed unnecessary. 
     The power drive system according to the preferred embodiment of the present invention has been illustrated herein in a schematic manner for clarity. Many components of this system were not illustrated to facilitate the understanding of the basic concept of this invention. The components that were not illustrated are those for which the nature, the mounting and functions would be obvious to the persons skilled in the art of electronics and machine design in general. Similarly, the physical dimensions, material types and manufacturing tolerances are not provided because these details are considered obvious to the skilled artisan.