Abstract:
A priority hydraulic flow diverter control assembly for a refuse collection vehicle hydraulic system provides proper and efficient flow in an auxiliary hydraulic circuit regardless of the primary flow so that refuse cart lifters and the refuse cart operate safely and efficiently. A pressure sequence valve diverts hydraulic fluid flow from the refuse cart lifter circuit into the downstream main hydraulic system when downstream back pressure is low, and into the system tank when back pressure is high. This allows all hydraulic operated equipment to operate at their intended speed whether at high or low system back pressure. 
     A differential pressure sensing valve and flow regulating valves provide a precision flow. Harmful and undesirable vibrations and noise associated with pulses in hydraulic system pressure are reduced using a control orifice located in the valve body. A relief valve ensures that the diverter control assembly is compatible with other manufacturer&#39;s products.

Description:
RELATED APPLICATIONS 
     This application makes reference to, claims priority to, and claims the benefit of U.S. Provisional Patent Application Ser. No. 60/650,021, entitled “Priority Hydraulic Flow Diverter Valve”, filed Feb. 4, 2005, the complete subject matter of which is hereby incorporated herein by reference in its entirety. 
    
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     [Not Applicable] 
     MICROFICHE/COPYRIGHT REFERENCE 
     [Not Applicable] 
     BACKGROUND OF THE INVENTION 
     The present invention relates to hydraulic systems, and in particular to hydraulic systems used on refuse collection vehicles to compact refuse and operate auxiliary hydraulic equipment such as refuse cart lifting devices. 
     Refuse collection vehicle hydraulic systems are primarily used to operate a ram that drives a packer panel, which compacts refuse dumped into the refuse collection vehicle&#39;s hopper. Many refuse collection vehicles are often also equipped with hydraulically operated auxiliary equipment such as refuse cart lifters. Refuse cart lifters are commonly known as lifters or tippers because they assist the vehicle operator in lifting and tipping heavy refuse carts into the refuse collection vehicle hopper or intermediate container. 
     A flow diverting apparatus, is commonly used to divert hydraulic fluid flow out of the main hydraulic system into the lifter circuit that operates these refuse cart lifting devices. The use of a flow-diverting apparatus, such as a diverter control assembly, to control hydraulic fluid flow to auxiliary hydraulic circuits is well known to those familiar with the design and operation of hydraulic systems. 
     Flow can be diverted by numerous means. The simplest method involves nothing more than a tee fitting placed in line of one of the pressure lines, with the primary flow directed towards the packer panel ram and the tee flow being directed to the lifter circuit. There are, however, several problems associated with this type of simple system. For example, the simple tee system will not maintain a consistent flow to the refuse cart lifters. The flow to the refuse cart lifters will be proportional to the flow to the downstream functions (such as the refuse collection vehicle packer ram) based on the size of the hydraulic lines and the downstream back pressure. 
     As inlet flow increases, the outlet flows increase and remain proportional to each other. This is because mobile refuse collection equipment typically utilizes a positive displacement “power take off” pump to provide refuse collection vehicle hydraulic system flow and pressure. The amount of hydraulic fluid flow in the system varies with the speed of the pump, and the pump speed directly corresponds to the refuse collection vehicle engine speed. Thus, the simple tee system cannot control the amount of hydraulic fluid flow to the refuse cart lifters as pump speeds vary. 
     Hydraulic refuse cart lifters require more precise control of hydraulic fluid flow. The time of the refuse cart lifter operating cycle is critical to performance, life of the refuse cart lifter, and life of the refuse cart. Most refuse cart lifters require a flow of 2 to 2.5 gallons per minute (gpm). The simple tee system can be improved by placing an orifice in the outlet line to the refuse cart lifters. This will change the proportion of flow and restrict the flow to a more suitable level. 
     For example, diverter control assemblies may use a priority flow valve containing an orifice. However, the pressure required to operate the priority flow valve is high, causing a pressure drop across the block. In order to maintain a controlled flow to two refuse cart lifters, a flow divider valve may be used to evenly divide the flow provided by the priority flow valve. However, when the refuse cart lifter bottoms out or the flow divider valve fails, the priority flow valve will shut down flow to downstream functions. 
     Moreover, this configuration can require significantly more pressure to operate than the priority flow valve. In fact, the pressure drop is more than doubled in the dual refuse cart lifter configuration. The combination of the two devices causes the pressure drop in the valve to be very high (as high as 350 to 400 psi, or more in certain instances). However, all mobile refuse equipment is not the same. System flow rates can range from less than 20 gpm to more than 60 gpm. The simple tee system is therefore often equipped with an adjustable orifice so that the flow can be fine tuned to make the flow to the refuse cart lifters acceptable regardless of the flow coming in to the tee. This relatively inexpensive type of flow diverter technology is currently used in many systems, but presents many disadvantages when used to control flow to refuse cart lifters. 
     For example, once the flow to the refuse cart lifters is adjusted, it will still allow for the flow to vary with the primary system flow. This will cause the refuse cart lifters to operate at different speeds relative to the primary system flow. Moreover, the use of a variable orifice results in a significant pressure drop across the system. This causes a reduction in the pressure available to downstream operations and can noticeably affect their operation and performance. 
     Furthermore, the additional work being done to move the oil through this restriction is dissipated through heat. The addition of heat to the hydraulic system is generally unacceptable as it also reduces the performance of the system. It can also be dangerous and lead to potential component failures and possibly system fires. Finally, if the adjustable orifice is improperly adjusted, it may allow the refuse cart lifters to cycle too quickly and lead to premature lifter failure and cart damage, or even personal injury. 
     BRIEF SUMMARY OF THE INVENTION 
     The present priority hydraulic flow diverter control assembly eliminates many disadvantages of existing mobile refuse hydraulic flow control systems and gives flow priority to the auxiliary hydraulic circuit, regardless of the incoming flow. The present priority hydraulic flow diverter control assembly may provide precise flow regardless of the primary hydraulic system flow so that the refuse cart lifter and the refuse cart may operate properly and efficiently. 
     The present priority hydraulic flow diverter control assembly uses a differential pressure sensing valve and flow regulating valves to provide a precision flow. The flow regulating valves employ an orifice to meter hydraulic fluid flow to the refuse cart lifters. The differential pressure sensing valve may reduce the pressure differential across the flow regulating valve, but may also maintain the pressure differential required to allow the flow regulating valves to operate properly. 
     The failure mode of the differential pressure sensing valve and flow regulating valves may also be such that the valve can not block the downstream flow in any way. A relief valve may be used to ensure that the unit is compatible with other manufacturer&#39;s products. 
     A control orifice in the priority flow hydraulic diverter control assembly may stabilize the differential pressure sensing valve to keep it from modulating erratically which reduces vibrations and noise. The control orifice may compensate for flow variations due to pump characteristics in individual applications. 
     A pressure sequence valve may enable the system to operate in the most efficient manner with respect to pressure drop and flow loss. The pressure sequence valve may divert the hydraulic fluid into a line downstream of the refuse cart lifters when the downstream back pressure is low. This allows the hydraulically operated equipment in the refuse collection vehicle hydraulic system to operate at their intended speed. When the back pressure climbs to a predetermined set point, the pressure sequence valve may sense the increased back pressure and diverts the flow leaving the refuse cart lifters to the hydraulic system reservoir or tank. This may result in a significantly reduced pressure drop across the priority flow hydraulic diverter control assembly. 
     The design of the present priority flow hydraulic diverter control assembly may prevent variation of the hydraulic fluid flow in the refuse cart lifter hydraulic circuit as the pressure varies in the main refuse collection vehicle hydraulic system or packer ram hydraulic circuit. Thus, the refuse cart lifters may operate at a consistent speed relative to the primary system flow. This may prevent excessively fast cycle times that may cause personal injury, and prolongs the life of the refuse cart lifter and the refuse carts. The significant reduction in the pressure drop across the priority flow hydraulic diverter control assembly greatly reduces the work required to move hydraulic fluid through the orifice in the flow regulating valve that can lead to potential component failures and possibly system fires. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is an elevated rear view of a refuse collection vehicle equipped with two refuse cart lifters mounted to the rear of the vehicle. 
         FIG. 2  is a side view of refuse collection vehicle equipped with a refuse cart lifter mounted to the rear of the vehicle. 
         FIG. 3  is a first perspective view of the present priority flow diverter control assembly. 
         FIG. 4  is a second perspective view of the present priority flow diverter control assembly. 
         FIG. 5  is a third perspective view of the present priority flow diverter control assembly. 
         FIG. 6  is a fourth perspective view of the present priority flow diverter control assembly. 
         FIG. 7  is a fifth perspective view of the present priority flow diverter control assembly. 
         FIG. 8  is a sixth perspective view of the present priority flow diverter control assembly. 
         FIG. 9  is a perspective view illustrating the hydraulic connections between the present priority hydraulic flow diverter control assembly and a hand valve controlling a single refuse cart lifter. 
         FIG. 10  is a line schematic illustrating the components and hydraulic flow path associated with the present priority hydraulic flow diverter control assembly when configured for use with a single refuse cart lifter. 
         FIG. 11  is a perspective view illustrating the hydraulic connections between the present priority hydraulic flow diverter control assembly and hand valves controlling dual refuse cart lifters. 
         FIG. 12  is a line schematic illustrating the components and hydraulic flow path associated with the present priority hydraulic flow diverter control assembly when configured for use with dual refuse cart lifters. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference now will be made in detail to the embodiments of the invention, one or more examples of which are set forth below. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used on or with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations. Other objects, features and aspects of the present invention are disclosed in or are apparent from the following detailed description. It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention. 
     Referring to  FIG. 1 , a refuse collection vehicle  10  is equipped with a first refuse cart lifter  20  and a second refuse cart lifter  30 . Refuse cart lifters  20  and  30  depicted in  FIG. 1  are of a type manufactured by Bayne Machine Works, Inc. that are designed to lift refuse carts having an upper and a lower grab bar (not shown). This type of refuse cart lifter is shown by way of example only. The particular type of refuse cart lifter is not essential to the present priority flow hydraulic diverter control assembly. Furthermore, although refuse cart lifters  20  and  30  are depicted as mounted on the rear of the refuse collection vehicle, the present invention is equally applicable to lifters mounted at other locations on the refuse collection vehicle, e.g. the side of a side-loading refuse collection vehicle (not shown) or the front or side of a front-loading refuse collection vehicle utilizing an intermediate container (not shown). Accordingly, the term “refuse collection vehicle” is not limited to the rear-loading refuse collection vehicle  10  of  FIG. 1 . 
       FIG. 2  is a side view of the rear portion of rear-loading refuse collection vehicle  10  depicted in  FIG. 1 , including a first hand valve  40  and first refuse cart lifter  20 . Hydraulic fluid is supplied to a first hand valve  40  through hydraulic line  42 . Hand valve  40  can be operated to direct hydraulic fluid flow through hydraulic line  45  to raise some part of refuse cart lifter  20 , or through hydraulic line  47  to lower some part of refuse cart lifter  20 . The hydraulic fluid that flows to refuse cart lifter  20  through line  45  or line  47  returns to hand valve  40  through line  47  or  45  respectively, and returns to the hydraulic system from hand valve  40  through hydraulic line  43 . 
       FIGS. 3 through 7  depict a preferred embodiment of present priority flow hydraulic diverter control assembly  100  configured to divert hydraulic fluid flow to first refuse cart lifter  20 . The present priority flow hydraulic diverter control assembly  100  can also be configured to divert hydraulic fluid flow to dual refuse cart lifters as later discussed in reference to  FIGS. 11 and 12 . It should be understood that although the priority flow hydraulic diverter control assembly is depicted using threaded modular components, the various components may also be otherwise operatively connected to the present priority flow hydraulic diverter control assembly. By way of example only, the various valves and orifices described may be machined into the priority flow hydraulic diverter control assembly without departing from the scope of the invention. 
     Turning to  FIG. 4 , hydraulic fluid from the main hydraulic system of refuse collection vehicle  10  enters priority flow hydraulic diverter control assembly  100  through threaded inlet port  180 . Hydraulic fluid flows out of priority flow hydraulic diverter control assembly  100  to first refuse cart lifter  20  through threaded port  170 , and returns to priority flow hydraulic diverter control assembly  100  through threaded port  160  (see also  FIG. 3 ). 
     If priority flow hydraulic diverter control assembly  100  is configured for a second refuse cart lifter  30 , hydraulic fluid may also flow out of priority flow hydraulic diverter control assembly  100  to refuse cart lifter  30  through threaded port  175  (shown plugged in  FIGS. 3 through 8 ), and return to priority flow hydraulic diverter control assembly  100  through threaded port  165  (shown plugged in  FIGS. 3-6  and  8 ). 
     Hydraulic fluid exits priority flow hydraulic diverter control assembly  100  into the main hydraulic system through threaded outlet port  185 . Threaded outlet port  190  (plugged in  FIGS. 3 ,  6  and  8 ) may be connected to the hydraulic system tank  192  (see  FIGS. 10 and 12 ). 
     Priority flow hydraulic diverter control assembly  100  components include a differential pressure sensing valve  110 , and a first flow regulating valve  120 . Both differential pressure sensing valve  110  and first flow regulating valve  120  are threaded into priority flow hydraulic diverter control assembly  100 . First flow regulating valve  120  contains an orifice sized to assist in maintaining the desired flow rate to refuse cart lifter  20 . Refuse cart lifters typically require a flow rate of 2.0 to 2.5 gpm. A threaded port  125  for a second flow regulating valve  127  (see  FIG. 8 ) is shown blocked by second flow regulating valve plug  126 . In a dual refuse cart lifter configuration, second flow regulating valve  127  would be installed in place of second flow regulating valve plug  126  (see  FIGS. 8 ,  11  and  12 ). 
     Differential pressure sensing valve  110  is a spring-loaded valve designed to establish flow through flow regulating valve  120  at low hydraulic pressures, and open a path around flow regulating valve  120  at high hydraulic pressures. Thus, differential pressure sensing valve  110  establishes the necessary pressure drop that is required to allow flow regulating valve  120  to operate properly, without generating an excessively high differential pressure across flow regulating valve  120 . Using differential pressure sensing valve  110 , the pressure drop across flow regulating valve  120  can be reduced to as low as 120 pounds per square inch (psi) in any configuration. 
     Threaded fitting  145  secures control orifice  147  in priority flow hydraulic diverter control assembly  100  ( FIG. 8 ). The pressure downstream of control orifice  147  adds to the spring force of differential pressure sensing valve  110  opposing the force on differential pressure sensing valve  110  resulting from the pressure in line  182  ( FIG. 9 ). Control orifice  147  ( FIG. 8 ) is included to prevent differential pressure sensing valve  110  from modulating erratically when used in different existing hydraulic systems. Erratic modulation is caused by pressure pulses resulting from slippage of the hydraulic pump in some systems. As the pressure increases and decreases with the frequency of the pressure pulses, the pressure downstream of control orifice  147  acts as feedback to differential pressure sensing valve  110  to prevent severe modulations in the pressure differential across flow regulating valve  120 . 
     Control orifice  147  may also be machined into priority flow hydraulic diverter control assembly  100  (not shown) and may prevent erratic modulation in most applications. In some cases, however, a particular hydraulic system may require a different size orifice to correct the unique modulation of the system. Thus, a single control orifice that is adjustable in size (not shown) may be used to try to match the characteristics of each individual truck hydraulic system. Preferably, however, a non-adjustable control orifice  147  that can be swapped out for a different sized non-adjustable control orifice  147  is preferred. 
     Priority flow hydraulic diverter control assembly  100  also includes an adjustable, spring-loaded relief valve  130  that is designed to relieve hydraulic pressure within priority flow hydraulic diverter control assembly  100  when a particular hydraulic pressure is reached. Hydraulic pressure within priority flow hydraulic diverter control assembly  100  may rise dramatically for several reasons. For example, hydraulic pressure within priority flow hydraulic diverter control assembly  100  will greatly increase when flow through priority flow hydraulic diverter control assembly  100  is blocked. This can occur when the operator of refuse cart lifter  20  “bottoms out” hand valve  40  ( FIG. 2 ). 
     Hydraulic pressure within priority flow hydraulic diverter control assembly  100  will also greatly increase if refuse cart lifter  20  is attempting to lift a particularly heavy refuse cart. Moreover, the attempted lifting of such a heavy refuse cart may damage the refuse cart. Thus, relief valve  130  is typically adjusted to relieve hydraulic pressure within priority flow hydraulic diverter control assembly  100  that occurs when refuse cart lifter  20  attempts to lift a refuse cart weighing 350 lbs or greater. 
     Pressure sequence valve  140  and relief valve  130  are preferably manufactured using different thread sizes to prevent the accidental switching of pressure sequence valve  140  and relief valve  130  during assembly of priority flow hydraulic diverter control assembly  100 . Incorrect assembly could ultimately cause equipment damage or personal injury. 
     Pressure sequence valve  140  enables the system to operate in the most efficient manner with respect to pressure drop and flow loss. Pressure sequence valve  140  senses the pressure from the main hydraulic system within priority flow hydraulic diverter control assembly  100  near outlet port  185 . Pressure sequence valve  140  recycles hydraulic fluid from refuse cart lifter  20  back to the main hydraulic system for use in driving the refuse collection vehicle packer ram, or other hydraulic equipment, when the pressure sensed in the main hydraulic system is low enough to permit the desired hydraulic fluid flow through refuse cart lifter  20 . 
     At a predetermined set point (typically where the pressure in the main hydraulic system is too high to permit enough hydraulic fluid flow through refuse cart lifter  20  to maintain normal lifter speed), pressure sequence valve  140  directs the fluid flow from refuse cart lifter  20  through outlet port  190  to the hydraulic system tank  192 . Thus, proper lifter speed may be maintained both above and below the predetermined set point. Packer ram operation is not significantly affected at this point because the hydraulic fluid flow required by the packer ram is typically low when the main hydraulic system pressure is high. The predetermined set point of pressure sequence valve  140  will vary by individual system, but many systems operate at a predetermined set point of around 1300 psi. 
     In the preferred embodiment, a spring force in pressure sequence valve  140  mechanically opposes the hydraulic force exerted by the hydraulic pressure from the main hydraulic system (see  FIGS. 10 and 12 ). Alternatively, an electronic signal representing the hydraulic pressure in the main hydraulic system generated by a pressure transducer (not shown) or the like may be compared against a predetermined electronic set point to direct flow through pressure sequence valve  140 . 
     A check valve  195  is threaded into priority flow hydraulic diverter control assembly  100 . Check valve  195  prevents back flow from the main hydraulic system into priority flow hydraulic diverter control assembly  100  through outlet port  185 . 
     A threaded port  150  (shown in  FIG. 8 ) designed to accept a dual sequence valve  152  is machined into priority flow hydraulic diverter control assembly  100 . Dual sequence valve plug  151  is shown installed in the single lifter configuration depicted in  FIGS. 5 and 6 . Dual sequence valve  152  replaces dual sequence valve plug  151  in a dual lifter configuration (see  FIG. 8 ). 
     Dual sequence valve  152  is needed in the dual lifter configuration because if first refuse cart lifter  20  is building more pressure than the second refuse cart lifter  30 , e.g. because first refuse cart lifter  20  is lifting a heavier refuse cart than second refuse cart lifter  30 , second refuse cart lifter  30  may not receive sufficient flow to operate properly. To correct this situation, dual sequence valve  152  directs hydraulic fluid flow from downstream of first flow regulating valve  120  to provide hydraulic feedback to differential pressure sensing valve  110  and raise the hydraulic pressure upstream of flow regulating valves  120  and  127 . This helps to maintain the operability of both refuse cart lifters  20  and  30  despite the increased pressure build up associated with first refuse cart lifter  20 . 
       FIG. 9  depicts the hydraulic connection between the main components of a typical refuse cart lifter hydraulic circuit configured to operate a first refuse cart lifter  20 . The refuse collection vehicle hydraulic system pump (not shown) pumps hydraulic fluid through supply line  182  and into priority flow hydraulic diverter control assembly  100  at threaded connection  180 . Hydraulic fluid flow metered by priority flow hydraulic diverter control assembly  100  flows to a first hand valve  40  through line  42 . Depending on the position of first hand valve  40 , hydraulic fluid flow may continue to first refuse cart lifter  20  through line  45  if first refuse cart lifter  20  is being raised, or line  47  if first refuse cart lifter  20  is being lowered. If first hand valve  40  is positioned to block hydraulic fluid flow to first refuse cart lifter  20 , hydraulic fluid flow may be diverted to an outlet of priority flow hydraulic diverter control assembly  100  via diverter control assembly relief valve  130  or first hand valve relief valve  41  (see  FIG. 10 ). 
     Hydraulic fluid flow from first refuse cart lifter  20  returns to first hand valve  40  through line  47  if first refuse cart lifter  20  is being raised, or line  45  if first refuse cart lifter  20  is being lowered. Hydraulic fluid returned to first hand valve  40  flows back to priority flow hydraulic diverter control assembly  100  through line  43 . Hydraulic fluid from priority flow hydraulic diverter control assembly  100  returns to either the main hydraulic system through line  187  or the hydraulic system tank  192 . The flow path from priority flow hydraulic diverter control assembly  100  depends upon the position of pressure sequence valve  140 . 
     Turning to  FIG. 10 , this figure is helpful in understanding the operation of priority flow hydraulic diverter control assembly  100  and its individual components, including the hydraulic fluid flow path within priority flow hydraulic diverter control assembly  100  when priority flow hydraulic diverter control assembly  100  is configured to operate a first refuse cart lifter  20 . 
     The refuse collection vehicle hydraulic system pump (not shown) pumps hydraulic fluid through supply line  182  and into priority flow hydraulic diverter control assembly  100  at threaded connection  180 . Flow is then directed into first flow regulating valve  120 . A portion of the flow out of flow regulating valve  120  is metered by control orifice  147  to differential pressure sensing valve  110 . If the hydraulic pressure in line  182  is high enough to overcome the spring force of differential pressure sensing valve  110  and the force applied to differential pressure sensing valve  110  by pressure downstream of control orifice  147 , a portion of the flow from line  182  will flow through differential pressure sensing valve  110  to main hydraulic supply line  187 . This keeps the differential pressure across priority flow hydraulic diverter control assembly  100  low, but adequate for refuse cart lifter operation. 
     Hydraulic fluid exits priority flow hydraulic diverter control assembly  100  at threaded port  160  and flows towards first hand valve  40 . If the hydraulic pressure downstream of flow regulating valve  120  is high enough to overcome the spring force of relief valve  130  or hand valve relief valve  41 , i.e. meets or exceeds the set point of relief valves  130  or  41 , hydraulic fluid will flow either back to the main hydraulic system through port  185  or to the hydraulic system tank  192  through port  190 . The flow path taken by the hydraulic fluid from the outlet of relief valve  130  is dependent on the set point of pressure sequence valve  140  and the hydraulic pressure in line  187 . If the hydraulic pressure in line  187  is high enough to overcome the spring force of pressure sequence valve  140 , i.e. meets or exceeds the predetermined set point of pressure sequence valve  140 , hydraulic fluid will flow to the hydraulic system tank  192  through port  190 . If the hydraulic pressure in line  187  is not high enough to overcome the spring force of pressure sequence valve  140 , i.e. is below the predetermined set point of pressure sequence valve  140 , hydraulic fluid will flow to the main hydraulic system through port  185 . 
     If the hydraulic pressure downstream of flow regulating valve  120  does not actuate relief valve  130  or hand valve relief valve  41 , hydraulic fluid flow may continue to first refuse cart lifter  20  through line  45  if the hand valve is positioned to raise the lifter, or line  47  if the hand valve is positioned to lower the lifter. Hydraulic fluid flow from first refuse cart lifter  20  returns to first hand valve  40  through line  47  if the operator raises the lifter, or line  45  if the operator lowers the lifter. Hydraulic fluid returned to first hand valve  40  flows back to priority flow hydraulic diverter control assembly  100  through line  43 . Hydraulic fluid from priority flow hydraulic diverter control assembly  100  returns to either the main hydraulic system through line  187  or the hydraulic system tank  192 , again dependent on the set point of pressure sequence valve  140  and the hydraulic pressure in line  187 . Check valve  195  prevents backflow from main hydraulic system line  187  into priority flow hydraulic diverter control assembly  100 . 
       FIG. 11  depicts the hydraulic connection and hydraulic fluid flow path between the main components of a typical refuse cart lifter hydraulic circuit configured to operate a first refuse cart lifter  20  and a second refuse cart lifter  40 . The refuse collection vehicle hydraulic system pump (not shown) pumps hydraulic fluid through supply line  182  and into priority flow hydraulic diverter control assembly  100  at threaded connection  180 . Hydraulic fluid flow metered by priority flow hydraulic diverter control assembly  100  flows to a first hand valve  40  through line  42 , and a second hand valve  50  through line  52 . Depending on the position of first and second hand valves  40  and  50 , hydraulic fluid flow may continue to first and/or second refuse cart lifters  20  and  30  through lines  45  and/or  55  respectively if the operator wishes to raise the lifter, or lines  47  and/or  57  respectively if the operator wishes to lower the lifter. If first and second hand valves  40  and  50  are positioned to block hydraulic fluid flow to first and second refuse cart lifters  20  and  30 , hydraulic fluid may be diverted downstream of first and second refuse cart lifters  20  and  30  via diverter control assembly relief valve  130  or hand valve relief valves  41  and  51  (see  FIG. 12 ). 
     Hydraulic fluid flow from first refuse cart lifter  20  returns to first hand valve  40  through line  47  if the operator raises the lifter, or line  45  if the operator lowers the lifter. Hydraulic fluid returned to first hand valve  40  flows back to priority flow hydraulic diverter control assembly  100  through line  43 . Hydraulic fluid flow from second refuse cart lifter  30  returns to second hand valve  50  through line  57  if the operator raises refuse cart lifter  30 , or line  55  if the operator lowers refuse cart lifter  30 . Hydraulic fluid returned to second hand valve  50  flows back to priority flow hydraulic diverter control assembly  100  through line  53 . 
     Again, priority flow hydraulic diverter control assembly  100  returns the hydraulic fluid flowing from refuse cart lifters  20  and  30  to either the main hydraulic system through line  187  or the hydraulic system tank  192 . The flow path from priority flow hydraulic diverter control assembly  100  depends upon the position of pressure sequence valve  140 . 
       FIG. 12  is used to explain the operation of priority flow hydraulic diverter control assembly  100  and its individual components, including the hydraulic fluid flow path within priority flow hydraulic diverter control assembly  100 , when priority flow hydraulic diverter control assembly  100  is configured to operate a first refuse cart lifter  20  and a second refuse cart lifter  30 . As in the single lifter configuration, refuse collection vehicle hydraulic system pump (not shown) pumps hydraulic fluid through supply line  182  and into priority flow hydraulic diverter control assembly  100  at threaded connection  180 . Flow is then directed into a first flow regulating valve  120  and a second flow regulating valve  127 . The flow regulating valve having the highest hydraulic pressure immediately downstream of the flow regulating valve will position dual sequence valve  152  to direct a portion of the flow out of that flow regulating valve to differential pressure sensing valve  110 . 
     If the hydraulic pressure in line  182  is high enough to overcome the spring force of differential pressure sensing valve  110  and the force applied to differential pressure sensing valve  110  by pressure downstream of control orifice  147 , a portion of the flow from line  182  will flow through differential pressure sensing valve  110  to main hydraulic supply line  187 . This keeps the differential pressure across flow regulating valves  120  and  127  low, but adequate for normal operation of both first refuse cart lifter  20  and second refuse cart lifter  30 . 
     Hydraulic fluid from first flow regulating valve  120  exits priority flow hydraulic diverter control assembly  100  at threaded port  160  and may flow via line  42  towards first hand valve  40 . Similarly, hydraulic fluid from second flow regulating valve  127  exits priority flow hydraulic diverter control assembly  100  at threaded port  165  may flow via line  52  towards second hand valve  50 . If the hydraulic pressure immediately downstream of flow regulating valves  120  or  127  is high enough to overcome the spring force of relief valve  130  or hand valve relief valves  41  and  51 , i.e. meets or exceeds the set point of relief valves  130 ,  41 , or  51 , hydraulic fluid from one or both of flow regulating valves  120  and  127  will flow either back to the main hydraulic system through port  185  or to the hydraulic system tank  192  through port  190 . The flow path taken by the hydraulic fluid from the outlet of relief valves  130 ,  41  and  51  is dependent on the predetermined set point of pressure sequence valve  140  and the hydraulic pressure in line  187 . 
     Similar to the single lifter configuration of priority flow hydraulic diverter control assembly  100 , if the hydraulic pressure in line  187  is high enough to overcome the spring force of pressure sequence valve  140 , i.e. meets or exceeds the predetermined set point of pressure sequence valve  140 , hydraulic fluid exiting priority flow hydraulic diverter control assembly  100  will flow to the hydraulic system tank  192  through port  190 . If the hydraulic pressure in line  187  is not high enough to overcome the spring force of pressure sequence valve  140 , i.e. is below the predetermined set point of pressure sequence valve  140 , hydraulic fluid will flow to the main hydraulic system through port  185 . 
     If the hydraulic pressure downstream of flow regulating valves  120  and  127  does not actuate relief valves  130 ,  41 , or  51 , hydraulic fluid flow may continue to first refuse cart lifter  20  through line  45  if first hand valve  40  is positioned to raise first refuse cart lifter  20 , or line  47  if first hand valve  40  is positioned to lower first refuse cart lifter  20 . Similarly, hydraulic fluid flow may continue to second refuse cart lifter  30  through line  55  if second hand valve  50  is positioned to raise second refuse cart lifter  30 , or line  47  if second hand valve  50  is positioned to lower second refuse cart lifter  30 . Hydraulic fluid flow from first refuse cart lifter  20  returns to first hand valve  40  through line  47  if the operator raises the lifter, or line  45  if the operator lowers the lifter. 
     Hydraulic fluid returned to first hand valve  40  flows back to priority flow hydraulic diverter control assembly  100  through line  43 . Similarly, hydraulic fluid returned to second hand valve  50  flows back to priority flow hydraulic diverter control assembly  100  through line  53 . Hydraulic fluid from priority flow hydraulic diverter control assembly  100  returns to either the main hydraulic system through line  187  or the hydraulic system tank  192 , again dependent on the set point of pressure sequence valve  140  and the hydraulic pressure in line  187 . Check valve  195  prevents backflow from main hydraulic system line  187  into priority flow hydraulic diverter control assembly  100 . 
     Although the present priority flow hydraulic diverter control assembly  100  has been described using specific terms, devices, and methods, such description is for illustrative purposes only. The words used are words of description rather than of limitation. It is to be understood that changes and variations may be made by those of ordinary skill in the art without departing from the spirit or the scope of the present invention, which is set forth in the following claims. In addition, it should be understood that aspects of the present priority flow hydraulic diverter control assembly may be interchanged both in whole or in part. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained therein.