Patent Publication Number: US-2023150560-A1

Title: Delivery systems for ramps or stairs

Description:
BACKGROUND 
     In the delivery industry box trucks are becoming a common choice to make many types of deliveries. They offer value over tractor trailers for many delivery routes because drivers do not need a commercial driver license to operate them (large labor pool, non-specialized), and typically box trucks are cheaper to operate and are more maneuverable than tractor trailers. 
     A major challenge with box truck deliveries is transporting product from the elevated truck bed to ground level. To overcome this, box trucks are equipped with either a hydraulic liftgate, or a long (10-14′) ramp which is stowed underneath the truck while in route. 
     At times, the product must also be transported up or down stairs, which is not possible with a traditional pallet jack and which is difficult with a dolly. 
     SUMMARY 
     The delivery system improves safety and delivery efficiency over current state, where ramps are used, to reduce operator injury and spills by keeping the load level while moving up and down the ramp. Another embodiment of the delivery system makes it easier to bring a load up or down stairs. 
     In some aspects, the techniques described herein relate to a pallet lift including: a base; a deck extending forward of the base; load wheels supporting the deck; and a platform above the deck and pivotable relative to the base, wherein the platform has an upper support surface for supporting objects thereon. 
     In some aspects, the techniques described herein relate to a pallet lift further including a backrest extending upward from the platform, wherein the backrest is pivotably secured to the base. 
     In some aspects, the techniques described herein relate to a pallet lift further including an actuator configured to pivot the platform relative to the base. 
     In some aspects, the techniques described herein relate to a pallet lift wherein the platform is pivotable about an axis parallel to axes of the load wheels. 
     In some aspects, the techniques described herein relate to a pallet lift further including a rear wheel mounted below the base and pivotable relative to the base by a tiller arm. 
     In some aspects, the techniques described herein relate to a pallet lift further including a gravity sensor configured to detect its orientation relative to gravity. 
     In some aspects, the techniques described herein relate to a pallet lift further including a controller configured to automatically cause the platform to pivot relative to the base based upon a gravity signal from the gravity sensor. 
     In some aspects, the techniques described herein relate to a pallet lift further including a speed sensor configured to detect a speed of the pallet lift and to generate a speed signal indicative of the speed of the pallet lift, wherein the pallet lift further includes at least one motor for powering at least one of the load wheels, wherein the controller is configured control a speed of the at least one motor based upon the speed signal from the speed sensor. 
     In some aspects, the techniques described herein relate to a pallet lift wherein the controller is configured to control the speed of the at least one motor based upon the gravity signal. 
     In some aspects, the techniques described herein relate to a pallet lift wherein the load wheels are secured to arms pivotably secured to the deck. 
     In some aspects, the techniques described herein relate to a pallet lift further including: at least one camera mounted to the deck; and a display mounted to the base, the display configured to display a live view from the at least one camera. 
     In some aspects, the techniques described herein relate to a method for moving a load including: a) moving a load on a platform onto an inclined ramp; b) pivoting the load and the platform relative to wheels supporting the platform on the inclined ramp; and c) moving the load on the platform across the inclined ramp while the load and the platform are pivoted relative to the wheels. 
     In some aspects, the techniques described herein relate to a method wherein the platform is substantially perpendicular to gravity during step c). 
     In some aspects, the techniques described herein relate to a method wherein the inclined ramp is inclined more than ten degrees. 
     In some aspects, the techniques described herein relate to a pallet lift including: a base; at least one rear wheel supporting the base; a platform extending forward from the base; and a load wheel secured to an arm pivotably secured to the platform, wherein the arm is configured to move the load wheel toward and away from the platform thereby pivoting the platform relative to a surface on which the at least one rear wheel and the load wheel are supported. 
     In some aspects, the techniques described herein relate to a pallet lift wherein the arm is able to move the load wheel toward and away from the platform without moving the at least one rear wheel relative to the base. 
     In some aspects, the techniques described herein relate to a stair climbing device including: a base; a motor mounted to the base; and a plurality of rods configured to be rotatably driven by the motor about an axis perpendicularly to the plurality of rods. 
     In some aspects, the techniques described herein relate to a stair climbing device in combination with a hand cart, wherein the stair climbing device is secured to the hand cart. 
     In some aspects, the techniques described herein relate to a method for stabilizing a load including: a) supporting a load on a platform; b) detecting a change in orientation of the platform; and c) pivoting the platform relative to a surface on which the platform is supported to counteract the change in orientation detected in step b). 
     In some aspects, the techniques described herein relate to a method wherein the change in orientation in step b) is caused by wheels supporting the platform being supported on an inclined surface. 
     In some aspects, the techniques described herein relate to a method wherein step c) further includes pivoting the platform relative to the wheels to maintain the platform substantially perpendicular to gravity. 
     In some aspects, the techniques described herein relate to a method wherein the platform is connected to a backrest and wherein the platform and backrest are pivoted in step c). 
     In some aspects, the techniques described herein relate to a method wherein the platform and backrest are pivoted away from the inclined surface in step c). 
     In some aspects, the techniques described herein relate to a pallet lift having: a base; at least one rear wheel supporting the base; a platform extending forward from the base; a camera mounted proximate a front of the pallet lift; a display oriented generally rearward of the pallet lift, the display configured to provide a live video feed from the camera; and a load wheel secured to an arm pivotably secured to the platform, wherein the arm is configured to move the load wheel toward and away from the platform. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a ramp delivery system according to a first embodiment, which is a pallet lift. 
         FIG.  2    shows the pallet lift of  FIG.  1    with the platform raised relative to the load wheels and the rear wheel. 
         FIG.  3    shows the pallet lift of  FIG.  2    supporting a pallet thereon. 
         FIG.  4    shows the pallet lift of  FIG.  1    moving down a ramp R. 
         FIG.  5    shows the pallet lift of  FIG.  1    traveling up the ramp R (or other incline). 
         FIG.  6    shows the pallet lift of  FIG.  1    carrying a pallet down a ramp. 
         FIG.  7    shows the pallet lift carrying products up an incline (such as a ramp). 
         FIG.  8    shows a ramp delivery system according to a second embodiment, which is a pallet lift, traveling down a ramp. 
         FIG.  9    shows the pallet lift of  FIG.  8    traveling up an incline. 
         FIGS.  10  and  11    show a third embodiment of a ramp delivery system, which is again a pallet lift, traveling at an angle down a ramp. 
         FIG.  12    shows a delivery system according to another embodiment. 
         FIG.  13    shows the stair climbing device of  FIG.  12   . 
         FIG.  14    shows the stair climbing device separated and hand cart of  FIG.  12    disconnected from one another. 
         FIG.  15    shows another embodiment of a ramp delivery system, which is a pallet lift. 
         FIG.  16    is a side view of the pallet lift in the raised position, such as would be used to raise a pallet. 
         FIG.  17    shows the pallet lift of  FIG.  16    traveling down a ramp. 
         FIG.  18    is a front view of the pallet lift of  FIG.  15   . 
         FIG.  19    is a front view of the pallet lift of  FIG.  15    with the platform tilted back. 
         FIG.  20    is a front view of the pallet lift of  FIG.  17   , with the tines raised, the platform tilted back and with an optional camera. 
         FIG.  21    is a front perspective view of the pallet lift of  FIG.  15   . 
         FIG.  22    is a front perspective view of the pallet lift of  FIG.  19   . 
         FIG.  23    is a front perspective view of the pallet lift of  FIG.  17   . 
         FIG.  24    is a side view of the pallet lift of  FIG.  17   . 
         FIG.  25    is a bottom perspective view of the pallet lift. 
         FIG.  26    is a partially exploded view of the pallet lift with the platform removed for visibility. 
         FIG.  27    is a partially exploded upper rear view of the base of the pallet lift. 
         FIG.  28    is a partially exploded front view of the base of the pallet lift. 
         FIG.  29    shows one possible schematic of the pallet lift. 
         FIG.  30    shows the pallet lift carrying a pallet on the platform down a ramp between a truck and ground. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a ramp delivery system according to a first embodiment, which is a pallet lift  10 . The pallet lift  10  includes a base  12  and a platform  14  extending forward from the base  12 . A tiller arm  16  is pivotably connected to the base  12  and is used to steer and control the pallet lift  10 . A rear wheel  18  is mounted below the base  12  and may be pivoted by the tiller arm  16 . Load wheels  20  (preferably two, but only one is visible) support the platform  14 . The platform  14  may comprise a single, continuous structure or a pair of spaced-apart tines. 
     The rear wheel  18  and/or the load wheels  20  may be motorized, such as by having hub motors therein to drive, brake and control the pallet lift  10 . The pallet lift  10  may take the form of a pallet jack, with hydraulics or electric motors or actuators configured to lift the platform  14  relative to the floor, such as by pivoting the load wheels  20  away from the platform  14 . 
     As shown in  FIG.  2   , the pallet lift  10  raises the platform relative to the load wheels  20  and the rear wheel  18 . In this embodiment, the load wheels  20  are rotatably connected at the ends of arms  22  that are pivotably connected to the platform  14  about an axis  24 . Rotation of the arms  22  by a front actuator  32 , which may be a hydraulic cylinder or electric motor or linear actuator or other suitable device, causes the platform  14  to lift relative to the load wheels  20 . This is similar to existing pallet jacks, but the arms  22  are substantially longer (e.g. more than 12″, and in the range of 12″ to 30″). Also, unlike existing pallet jacks, a separate rear actuator  30  (which again may be a hydraulic cylinder or electric motor or linear actuator or other suitable device) lifts the base  12  of the pallet lift  10  relative to the rear wheel  18 . The base  12  can be raised and lowered relative to the rear wheel  18  and the platform  14  can be raised and lowered relative to the load wheels  20 . Because they have their own actuators  30 ,  32 , the front and rear of the pallet lift  10  can be raised and lowered independently of one another, or together (as in  FIG.  2   ). 
     As shown in  FIG.  3   , and as is known, the platform  14  can be used to lift a pallet  50  off a floor for moving the pallet  50 . In  FIG.  3   , the platform  14  is substantially parallel to the floor on which the pallet lift  10  is supported. It should be noted that a slight rearward tilt (e.g. approximately a degree or two) would be considered substantially parallel to the floor in this context. 
     Referring to  FIG.  4   , when the pallet lift  10  is moving down a ramp R, the front actuator  32  ( FIG.  2   ) rotates the arms  22  to extend the load wheels  20  downward far enough to keep the platform  14  level relative to the earth. The base  12  is not raised relative to the rear wheel  18  (or at least, not as much). This keeps the platform  14  level, i.e. substantially perpendicular to gravity, and the load (not shown) stable on the platform  14 . While traveling down the ramp R, the motors on the load wheels  20  and/or rear wheel  18  control the pace of the descent. 
     Thus, in this embodiment, the rear actuator  30  for raising the base  12  relative to the rear wheel  18  can be activated independently of the front actuator  32  for raising the platform  14  relative to the load wheels  20 , and vice versa. The platform  14  is both raised above the floor (e.g. to lift a pallet off the floor) and maintained to be level relative to earth. 
     In one embodiment, sensors on the pallet lift  10  (e.g. a two-axis accelerometer, a three-axis accelerometer and/or gyroscope in the base  12  or on the platform  14 ) are configured to detect the direction of gravity. Based upon a determined direction of gravity, a controller (which may include a processor or hardwired control circuitry or control logic) is programmed to maintain the sensors, the base  12 , and/or the platform  14  normal to the direction of gravity by adjusting the relative height between the platform  14  and the load wheels  20  and the relative height between the base  12  and the rear wheel  18 . One method of automatically leveling the load while the pallet lift  10  navigates non-level surfaces could be detecting the difference between the normal vector of pallet lift  10  platform and the gravitational normal vector, then adjusting the platform  14  tilt angle in real time to keep both vectors parallel so that the load is level. 
     In one embodiment, the lift height and tilt angle could be controlled by the same actuator, such that the initial displacement results in vertical lift (or substantially vertical lift) and further displacement results in tilting (or much more substantial tilting) of the load platform. This could be accomplished by cams, gears, levers, etc. 
     In another embodiment the amount of lift and amount of tilt could be controlled separately and operated as two separate systems. 
     The lift and tilt could also be operated manually, hydraulically, electrically, pneumatically or a combination of all. The auto tilt could be turned on by a button, switch, or automatically turn on after sensing the system is on a grade. 
     The pallet lift  10  could use a platform  14  which can lift a pallet  50  or allow product to be set directly on the platform. The platform  14  could have features which interlock with a pallet  50  to prevent the pallet  50  from sliding off. 
     The platform  14  could also have features to prevent loose product from sliding off. Features could include rails, textured surfaces, locking belts or a combination. 
     In one embodiment the platform could contain a backrest to stabilize the load during use. 
     Referring to  FIG.  5   , the pallet lift  10  may also be configured to provide leveling of the platform  14  while the pallet lift  10  is traveling up the ramp R (or other incline). In  FIG.  5   , the distance between the base  12  and the rear wheel  18  is increased by the rear actuator  30  ( FIG.  2   ) more than the distance between the platform  14  and the load wheels  20  by front actuator  32  ( FIG.  2   ). This can be implemented because the actuators for raising the base  12  and raising the platform  14  are independent of one another. Again, the actuators could be controlled by a microprocessor or hardwired circuitry or control logic based upon one or more sensors (such as a three-axis accelerometer and optionally a gyroscope) in the base  12  that determines the direction of gravity and maintains the platform  14  orthogonal to gravity. 
       FIG.  6    shows the pallet lift  10  carrying a pallet  50  down a ramp. As shown, the arms  22  are pivoted downward substantially so that the load wheels  20  are moved a much greater distance from the platform  14  than the rear wheel  18  is moved from the base  12 . In this manner, the pallet  50  is maintained substantially level relative to earth. 
       FIG.  7    shows the pallet lift  10  carrying products  52  (in this example, boxes) up an incline (such as a ramp). Again, the sensors on the pallet lift  10  detect the direction of gravity and maintain the platform  14  orthogonal to gravity. In this case, the controller automatically causes the rear actuator  30  to extend the rear wheel  18  downward from the base  12  significantly more than the front actuator  32  extends the load wheels  20  from the platform  14 . Again, either or both the load wheels  20  and the rear wheel  18  can include a motor (such as a hub motor) for propelling the pallet lift  10  up the incline. 
       FIG.  8    shows a ramp delivery system according to a second embodiment, which is a pallet lift  110 . The pallet lift  110  includes the same base  12 , platform  14 , tiller arm  16 , rear wheel  18  and actuators  30 ,  32  ( FIG.  2   ) as before. The load wheels in this embodiment are each continuous track systems  120  each with a plurality of wheels  130 ,  132 ,  134  (in this example, three) all encircled by a tread  136 . A pair of arms  126 ,  128  extend away from a lower end of each arm  122 . The center wheel  134  is rotatably connected at a lower end of the arm  122 . The outer wheels  130 ,  132  are rotatably connected at ends of the arms  126 ,  128 . The continuous track systems  120  pivot relative to the lower end of the arm  122 . The continuous track systems  120  enable the pallet lift  110  to traverse up and down stairways, rough terrain, curbs, and uneven surfaces. Otherwise, the pallet lift  110  operates in the same way described above with respect to  FIGS.  1 - 7   . 
     For example, in  FIG.  8   , the pallet lift  110  is traveling down an incline so the front actuator  32  ( FIG.  2   ) extends the continuous track systems  120  from the platform  14  by a distance greater than the rear actuator  30  ( FIG.  2   ) extends the rear wheel  18  from the base  12  to maintain the platform  14  orthogonal to gravity. 
     in  FIG.  9   , the pallet lift  110  is traveling up an incline, so the rear wheel  18  extends further from the base  12  than the continuous track systems  120  does from the platform  14  to maintain the platform  14  level relative to earth. 
       FIGS.  10  and  11    show a third embodiment of a ramp delivery system, which is again a pallet lift  210 . Again, the base  12 , platform  14 , tiller arm  16  and rear wheel  18  may be the same as above. In the pallet lift  210 , the arms  222  are configured to be actuated independently from one another (as well as independently of the rear wheel  18 ). For example, there would be two front actuators  32 , one for each of the arms  222 . In this manner, the pallet lift  210  provides control of the tilt of the platform  14  about two axes. By extending one of the arms  222  more than the other, the pallet lift  210  can control the tilt of the platform  14  about the longitudinal axis of the platform  14  (roll). This can maintain the stability of a load on the platform  14  on uneven terrain, or if the pallet lift  210  travels at an angle down an incline as shown. Again, a three-axis accelerometer or two-axis accelerometer and/or other sensors, such as a gyroscope, can indicate the orientation of the pallet lift  210  relative to gravity and a controller on board the pallet lift  210  can deploy the rear wheel  18 , and each of the arms  222  an appropriate distance to maintain the platform  14  orthogonal (or substantially orthogonal) to gravity. 
     In one embodiment the load is kept level by tilting the load platform separately from the rest of the system, so that the system normal vector is parallel with the ramp normal vector and the load platform normal vector is parallel with the gravitational normal vector. 
     In another embodiment the wheels could lift independently, providing tilt to the whole lift or it could just tilt the platform. 
     The system could have a removable platform so that different sized platforms could be used with the same lift. This would allow the lift to be optimized for different load sizes or delivery needs. 
     The system could also have attachment points so that accessories to carry specialized containers can be quickly attached, such as a cylindrical racks to house beer kegs or CO2 bottles used in the beverage industry. 
     The system could be stowed either inside or outside the delivery vehicle on a specialized storage platform or enclosure which includes provisions to recharge the system and secure the system during transportation. 
     Battery charging could commence automatically once the system is in stowage. The charging method could be wireless, self-connecting magnetic plugs, large sprung pads that contact when stowed. 
     The platform or enclosure could have an integrated ramp so that a separate ramp is not needed. The ramp could be hinged, folding, or the stowage platform could be the ramp itself. The ramp could be counterweighted or spring assisted to make opening and closing easier. Counterweighting and assistance could be done with springs, pneumatically, hydraulically, or electrically. 
     In another embodiment the load could be automatically leveled by suspending the load platform similar to a swing and utilizing gravitational force to keep the load platform level. In this embodiment damper could be used to prevent the load from oscillating. 
     In a simple embodiment the amount of tilt could be controlled manually by the operator at his discretion either physically or electronically. The auto tilt could be turned on by a button, switch, or automatically turn on after sensing the system is on a grade. 
     In all of the embodiments described herein, it may be desirable to maintain the platform  14  in a desired orientation other than strictly orthogonal to gravity. For example, it may be desirable to achieve a desired orientation wherein the platform  14  is tilted back toward the base  12  (or a backrest) slightly for stability. Also, the desired orientation of the platform  14  may be any angle depending on what is being supported on the platform  14  and how/whether the item being supported on the platform  14  is secured to the platform  14 . 
     A delivery system  310  according to another embodiment is shown in  FIG.  12   . A standard hand cart  312  is shown having a support platform  314  a vertical support  316  and handles  318 . A pair of wheels  320  are mounted to a lower end of the vertical support  316 . 
     A stair climbing device  330  according to one embodiment is shown removably secured to the hand cart  312 . The detachable stair climbing device  330  allows a user to attach the device to the system (such as the hand cart  312 ) to safely and efficiently carry a load up and down stairs when needed, but have the benefits of a lighter and more maneuverable piece of equipment when not. 
     In this embodiment the stair climbing device  330  could be stored in the delivery vehicle and attached to a piece of equipment like a cart or hand cart  312  when the user needs to bring a load up or down stairs. 
     Referring to  FIG.  13   , the stair climbing device  330  includes a base  332 , such as a metal plate. A motor  334  is mounted to the base  332 . Rods  336  are mounted at opposite ends of the motor  334 . The rods  336  are perpendicular to the long axis of the motor  334 . When the motor  334  is activated, the rods  336  rotate about the long axis of the motor  334 . A battery  338  or other power source is mounted to the base  332  and is connected to the motor  334 . 
     The stair climbing device  330  could be powered electrically by the battery  338 . The battery  338  could be removeable or built in, and it could have charging features which make it convenient to be rechargeable in the delivery trailer. 
     In another embodiment, when it is used with delivery equipment other than the hand cart  312 , the stair climbing device  330  could utilize the power source of the equipment it is being used with. The stair climbing device  330  could plug into the equipment or the equipment battery could be transferred to the stair climbing device  330 . 
     In another embodiment the stair climbing device  330  could have a removable battery pack that could be charged by itself or within the stair climbing device  330 . 
     Alternatively, the stair climbing device  330  could operate by a mechanical device, such as leverage or friction. It could use a foot pedal to raise the load step by step. It could use friction to slow the descent. 
     In one embodiment the stair climbing device  330  could have sensors integrated into the body that detect when to climb or descend automatically. The sensors could be physical such as a limit switch, optical such as laser/lidar style, others such as sonar or a combination of them. In another embodiment, the stair climbing device  330  could communicate with the delivery equipment electronically or mechanically to detect when to climb or descend. 
     Referring to  FIG.  14   , the stair climbing device  330  can be selectively removed from the standard hand cart  312  so that the standard hand cart  312  can be used without the weight of the stair climbing device  330 . 
     The method of attachment could be mechanical, magnetic, or a combination of the two. In one embodiment latches and catches could be used on the stair climbing device  330  and hand cart  312  to secure the two together quickly. 
     In another embodiment the stair climbing device  330  could be provided with a mounting kit so that it could be mounted to a range of delivery equipment besides the hand cart  312 . 
     In another embodiment, the stair climbing device  330  could be a modular accessory to a powered piece of equipment and the quick attachment process could include a power plug to power the stair climbing device  330  from the main piece of equipment. 
     There could be controls on the stair climbing device  330  to climb or descend or the stair climbing device  330  could be controlled wirelessly by remote. 
     In one embodiment, the controls could be wired to the stair climbing device  330  and attach to the hand cart  312  for one handed operation. The control could attach with magnets, with Velcro straps, with a clasp, or another way of being secured to the hand cart  312  or other delivery equipment. 
     In another embodiment the control could be wireless and could be stored within the stair climbing device  330  then removed for use. The control could be battery operated and could be recharged by the hand cart  312  when not in use. 
     In another embodiment the controls could be built into the hand cart  312  or other delivery equipment, so that once the stair climbing device  330  is attached, they become active and functional. 
     In another embodiment, the stair climbing device  330  could attach magnetically and engage mounting features on the hand cart  312  (or other delivery equipment). 
       FIG.  15    shows another embodiment of a ramp delivery system, which is a pallet lift  410 . The pallet lift  410  includes a base  412  and a platform  414  extending forward from the base  412 . A backrest  415  extends upward from a rear end of the platform  414 . 
     A tiller arm  416  is pivotably connected to the base  412  and is used to steer and control the pallet lift  410 . A rear wheel  418  is mounted below the base  412  and may be pivoted by the tiller arm  416  to provide steering. Alternatively, the pallet lift  410  may have casters mounted below the base  412  and fixed handles could be mounted to the base  412  instead of the tiller arm  416 . 
     Load wheels  420  (preferably two, but only one is visible in  FIG.  15   ) support the platform  414 . The platform  414  may comprise a solid platform (as shown in this example) or a pair of spaced-apart tines, depending on the type of pallets to be used with the pallet lift  410 . Alternatively, in applications where a pallet will not be used and product will be placed directly on the platform  414 , the lift function is not necessary so the load wheels  420  and rear wheel  418  can be set at a fixed height and the lift actuator  430  would be eliminated. 
     The load wheels  420  may be motorized, such as by having hub motors therein to drive, brake and control the pallet lift  410 . Alternatively, or additionally, the rear wheel  418  may be motorized, such as by having a hub motor therein. The pallet lift  410  may in some aspects generally take the form of a pallet jack, with hydraulics or electric motors or actuators configured to lift the platform  414  relative to the floor. 
     The platform  414  and the backrest  415  are secured to one another or formed integrally to form a rigid L-shaped member. The backrest  415  is pivotably secured to the base  412  at an axis  440 . The axis  440  is horizontal, i.e. generally parallel to the floor and parallel to the axes of the load wheels  420 . 
       FIG.  16    is a side view of the pallet lift  410  in the raised position, such as would be used to raise a pallet (e.g. pallet  50  of  FIG.  3   ) off the floor. As is known, a lift actuator  430  lifts the base  412  relative to the rear wheel  418 . The lift actuator  430  may be a hydraulic cylinder, electric motor, linear actuator or other suitable actuator. Manual mechanical devices, such as levers and ratchets, could also be used. The lift actuator  430  is mounted between the rear wheel  418  and the base  412  and is configured to move the rear wheel  418  toward and away from the base  412  and, via linkage, to pivot the arms  442  and load wheels  420  toward and away from the tines  444 . The lift actuator  430  and its configuration for raising and lowering the tines  444  relative to the floor may be similar to a conventional pallet jack. 
     In  FIG.  17   , the load wheels  420  are still pivoted downward on arms  442  to raise the tines  444  and the platform  414 , and the rear wheel  418  is also moved away from the base  412 . Again, in this configuration, a pallet (not shown) supported on the platform  414  would be lifted from the floor for transport by the pallet lift  410 . As also shown in  FIG.  17   , the platform  414  and backrest  415  are pivotable relative to the base  412 . The upper end of the backrest  415  has been pivoted rearward about the axis  440 , thereby raising the front end of the platform  414 . 
     The pallet lift  410  is on a ramp R that is tilted relative to a horizontal plane of the floor/earth (which is perpendicular to gravity). The platform  414  and backrest  415  are pivoted rearward about axis  440  while the pallet lift  410  travels down the ramp R. Preferably the platform  414  and backrest  415  are pivoted so that the upper support surface of the platform  414  is parallel to the floor (i.e. perpendicular to gravity) or tilted rearward slightly (e.g. approximately two degrees, again, still considered substantially perpendicular to gravity). This may be performed automatically as described herein based upon sensor input, or this may be performed manually by the operator. In this manner, a load, such as a loaded pallet, will be stable on the pallet lift  410  as the pallet lift  410  travels down (or up) the ramp R. 
       FIGS.  18 - 20    are front views of the pallet lift  410 .  FIGS.  21 - 23    are front perspective views of the pallet lift  410 . In  FIGS.  18  and  21   , the platform  414  is in a lowered, horizontal position. In  FIGS.  19  and  22   , the platform  414  and backrest  415  are tilted rearward by a tilt actuator  446  secured to a forward end of the platform  414  and to the base  412 . When the tilt actuator  446  expands, the forward end of the platform  414  is lifted, thereby tilting the platform  414  and backrest  415  rearward relative to the base  412  and the tines  444  as shown. The tilt actuator  446  may be a hydraulic cylinder, electric motor, linear actuator, or other actuator. Manual mechanical devices, such as levers and ratchets, could also be used. 
     In  FIGS.  20 ,  23  and  24   , the tines  444 , base  412 , platform  414  and backrest  415  are raised upward relative to the floor and relative to the rear wheel  418  and the load wheels  420 . The platform  414  and backrest  415  are also tilted rearwardly relative to the base  412  and the tines  444 . 
     As can be seen in  FIGS.  20  and  23   , the tines  444  are spaced apart and extend separately from the base  412 . Together, the tines  444  can be considered a deck and the pair of spaced-apart tines could be secured to one another or replaced with a single, continuous deck.  FIG.  20    shows the pallet lift  410  with an optional camera  462  mounted to one of the tines  444  and facing forward of the pallet lift  410 . The camera  462  is mounted between the tines  444  in this example, but other locations may be suitable as well. 
       FIG.  25    is a bottom perspective view of the pallet sled  410 . Linkage  450  is coupled to each of a pair of push rods  448  leading to each arm  442 . As is known, the linkage  450  (via the lift actuator  430 ) forces the push rods  448  forward and rearward parallel to the tines  444 . As is known, the arms  442  are pivotably coupled to the tines  444  about an arm axis. The push rods  448  are also pivotably coupled to the arms  442  at a pushrod axis offset from the arm axis. Forward and rearward motion of the push rods  448  thus causes the arms  442  to pivot relative to the tines  444 , thereby moving the load wheels  420  toward and away from the tines  444 . 
       FIG.  26    is a partially exploded view of the pallet lift  410  with the platform  414  removed for visibility. The tines  444  extend forward from the base  412 . The tilt actuator  446  is pivotably coupled to the base  412  between the tines  444 . The push rods  448  are configured to be pivotably coupled to the arms  442  at pushrod axes offset from the arm axes about which the arms  442  pivot relative to the tines  444 . The optional camera  462  is shown mounted to one of the tines  444  and directed forward of the pallet lift  410 . 
       FIG.  27    is a partially exploded upper rear view of the base  412  of the pallet lift  410 . The lift actuator  430  is secured to a rear wall of the base  412 .  FIG.  27    shows an optional display  470  mounted to the base  412 , which faces the user during use. The display  470  could be part of a mobile device, such as a tablet having a processor  454  ( FIG.  29   ). 
       FIG.  28    is a partially exploded front view of the base  412  of the pallet lift  410 . Fasteners  452  provide a pivoting hinge connection along axis  440  between the backrest  415  and the base  412 . 
       FIG.  29    shows one possible schematic of the pallet lift  410 . A processor  454  may be mounted in the base  412 . The processor  454  is connected to electronic storage  456  storing computer instructions which when executed by the processor  454  causes the processor  454  to perform the functions described herein. Of course, the processor  454  could include a plurality of processors including processors of different types at different locations. 
     The processor  454  receives inputs from a tilt sensor  458 , which may be a three-axis or two-axis accelerometer, or other sensor that generates a signal indicating its orientation relative to gravity. The tilt sensor  458  is mounted in a fixed orientation relative to the platform  414 . For example, the tilt sensor  458  may be mounted to the backrest  415  or to the platform  414 . At least one speed sensor  460  is mounted to one of the load wheels  420  and/or the rear wheel  418 . A camera  462  is mounted to one of the tines  444  (or otherwise to the deck below the platform) or to the platform  414 . The camera  462  provides continuous live video from the camera  462  to the processor  454  and then to the display  470  (or directly to the display  470 ). The processor  454  receives a signal from a user interface  464 , which may be a touchscreen (e.g. display  470 ), microphone, button, switch, keyboard, trackpad, mouse, etc. 
     The processor  454  sends control signals to the tilt actuator  446  and the lift actuator  430  in the manner described herein. The processor  454  also sends control signals to motors  466  coupled to or within one or both of the load wheels  420  or the rear wheel  418 . The processor  454  also controls a brake  468  (if provided) on one or more of the load wheels  420  and rear wheel  418 . 
     The processor  454  is configured to send live video from the camera  462  to a display  470  mounted to the backrest  415  or to the base  412 . The processor  454  may enhance the live video with guidelines to help the user steer the pallet lift  410 . The processor  454  is connected to a wireless communication circuit  472  such as cell data, wifi, Bluetooth, etc. 
       FIG.  30    shows the pallet lift  410  carrying a pallet  50  on the platform  414 . The pallet  50  is loaded with a stack of products  52 . A ramp R extends from a floor of truck T to ground G. The ramp R may be inclined more than ten degrees. As the pallet lift  410  moves from the relatively level floor T of a truck onto the inclined ramp R, the tilt sensor  458  senses the change in orientation of the backrest  415  and platform  414 . The processor  454  receives this signal from the tilt sensor  458  and commands the tilt actuator  446  to pivot the platform  414  and backrest  415  rearward until the tilt sensor  458  detects that the platform  414  is returned to generally level relative to gravity, i.e. perpendicular to gravity (or tilted rearward slightly, e.g. two degrees). As the load wheels  420  begin down the ramp R, the pallet lift  410  will gradually tilt and the pallet lift  410  will gradually extend the tilt actuator  446  pivoting the platform  414  more and more until the rear wheel  418  is also on the ramp R, which is when the pallet lift  410  will be tilted the most. Then, when the load wheels  420  reach the relatively level ground G, the pallet lift  410  will gradually return to level and the tilt actuator  446  will be gradually retracted, pivoting the platform  414  downward to maintain the platform  414  perpendicular to gravity (or tilted slightly rearward). When the rear wheel  418  reaches the ground G, the platform  414  will be returned to an orientation generally parallel to the tines  444 , again, substantially orthogonal to gravity. 
     As is apparent from  FIG.  30   , while the pallet lift  410  is traveling down the ramp R, it would be difficult for the operator to see past the products  52  on the pallet  50 . The optional camera  462  mounted to one of the tines  444  (or otherwise at the front of the deck) provides a live video feed of the area in front of the pallet lift  410  to the display  470  mounted to the base  412 .  FIG.  30    shows an alternate location for the camera  462   a , mounted to the front of the platform  414  (or just under the front of the platform  414 ). The camera  462  or camera  462   a  could also be used on level surfaces when the platform  414  are not tilted relative to the base  412 . 
     The display  470  could also have overlaid navigation lines that show the operator the expected path of the pallet lift  410  based upon a current orientation of the tiller arm  416  (or other steering mechanism). The operator would use the navigation lines to steer straight down the ramp or to estimate whether or not they will make a turn, similar to the backup cameras on modern vehicles. 
     Active Speed Control 
     During use of the pallet lift  410 , a fast speed (like fast walking speed) would be needed for use on flat ground G and a very slow speed (around 1 mph) would be needed to descend a ramp R safely. The processor  454  controls the speed of the pallet lift  410  by controlling the motor  466  (and the brake  468 , if provided,  FIG.  29   ). In  FIG.  30   , the motor  466  is shown as a standard electric pallet jack drive motor  466  connected to the rear wheel  418 . Hub motors within the load wheels  420  could be used as an alternative. 
     In order to improve ease of use and operator safety while descending a ramp, a speed limiter could be automatically implemented by the processor  454  once the pallet lift  410  detects that it is descending a ramp, such as by detecting a tilt in excess of a threshold by the tilt sensor  458 . 
     Optionally, the pallet lift  410  could also have a button or switch in the user interface  464  (shown in  FIG.  30    as a UI on display  470 , which may be a touch screen) which turns on “ramp mode” that activates the speed control and adjusts the previously mentioned Active Stability Control and Active Traction Control settings for optimal ramp settings. Pressing the “ramp mode” button may also enable the processor  454  to activate the tilt actuator  446  based upon input from the tile sensor  458 , such that when the tilt actuator  446  detects that it being tilted relative to gravity (e.g. as the pallet lift  410  goes down the ramp), the processor  454  receives this signal from the tilt actuator  446  and sends counteractive signals to the tilt actuator  446  to maintain the platform  414  perpendicular to gravity (or tilted slightly back). When the load wheels  420  hit the level ground after the ramp, the pallet lift  410  starts to return to level ground, which is detected by the tilt sensor  458 , so the processor  454  sends signals to the tilt actuator  446  to move the platform  414  back toward the tines  444  to maintain the upper surface of the platform  414  perpendicular to gravity (or tilted slightly back). 
     Active Stability Control 
     Since the stability of the pallet lift  410  is key to preventing a tip-over of the system, one embodiment could use the tilt sensor  458  to detect the side to side angle (roll) of the pallet lift  410  as well as the pitch, and if the angle of the lift is past a pre-determined safe angle, the electronic controller could take action to prevent tipping, such as slowing or stopping the pallet lift  410  by reducing power to the motors  466  or applying the brake  468 , lowering the load height by releasing the lift actuator  430 , increasing or decreasing the tilt angle by appropriately controlling the tilt actuator  446  or a combination thereof. 
     Active Traction Control 
     The pallet lift  410  may be driven on various surfaces in a range of conditions (hot, cold, rain, snow, aluminum ramps, steel ramps, pavement, concrete, dirt, wood etc.) and in order to improve traction, the processor  454  could detect drive wheel (in this case, the rear wheel  418 ) slip and take action to reduce the wheel slip and help regain control. This would be specifically helpful while on a ramp, since losing traction while descending the ramp would cause loss of steering and loss of speed control. 
     One method to detect drive wheel slip is by comparing the pallet lift  410  acceleration, as detected by an accelerometer (such as tilt sensor  458 ), to the drive wheel speed, as provided by the speed sensor  460  (which may be a drive wheel encoder) and comparing these inputs to a function which characterizes normal acceleration vs wheel speed. When a large enough delta between the actual acceleration vs expected acceleration exists, the electronic controller can take action to reduce wheel slip. 
     Active Load Control 
     The pallet lift  410  could sense the weight of the load and automatically adjust the previously mentioned Active Stability Control, Active Traction Control and Active Speed Control settings to suit the load. The load sensing could be done by measuring the line pressure of the hydraulic lifting mechanism of the tilt actuator  446  or by load cells placed under the load platform or by deriving it from the energy required to accelerate the load. 
     Equipment Guides 
     Since the ramps that the pallet lift  410  is used on are very narrow, it can be difficult to navigate without hitting the side guard rails of the ramp. To prevent damage to the pallet lift  410  or ramp, the pallet lift  410  could have side bumpers that contact the guard rails of the ramp before the rest of the pallet lift  410  does. By positioning the bumpers near the front and/or back of the pallet lift  410 , steering the pallet lift  410  straight down the ramp would no longer be required. 
     In one embodiment the bumpers could “sliders,” hard plastic or rubber material which slides along the side guard rail of the ramp. 
     In another embodiment the bumpers could be rolling wheels positioned to roll along the guard rails of the ramp when in contact. The rollers could be attached to the frame of the pallet lift  410  and used in a fixed fashion to keep the lift from driving too far to one side or the other. The rollers could also be attached to the steering mechanism so that when in contact with the side guard rails, the steering is pushed to steer away from the side guard rail. 
     A different embodiment could use a combination of rollers and sliders that allows the pallet lift  410  to drive down the ramp while in contact with the side guard rail the whole time without any risk of catching or damaging the lift or ramp. 
     In accordance with the provisions of the patent statutes and jurisprudence, exemplary configurations described above are considered to represent a preferred embodiment of the invention. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope. Alphanumeric identifiers on method claim steps are for ease of reference in dependent claims only and do not signify a required sequence of steps unless other explicitly recited in the claims.