referring to fig1 , a pick - up truck ( 1 ) of weight class one or two is conventionally powered by an internal combustion engine ( 2 ). the internal combustion engine ( 2 ) is configured with a front end accessory drive ( fead ) ( 3 ) consisting of a multi - grooved serpentine belt ( 5 ) arranged to drive a number of conventional ancillary components such as an alternator ( 4 ), water pump ( 6 ) and air conditioning compressor ( 7 ). the fead is additionally configured to drive a multi - piston fluid pump ( 11 ) capable of delivering hydraulic fluid under pressure . the multi - piston fluid pump ( 11 ) contains electrically selectable poppet valves configured to facilitate variable output . the electrically selectable poppet valves are powered via a microprocessor control ( 12 ) so that predetermined proportional hydraulic flow is supplied to a distribution valve block ( 13 ) by the multi - piston fluid pump ( 11 ). a reservoir ( 14 ) is connected so as to supply the pump with an adequate volume of hydraulic fluid at all demands as well as to receive returned hydraulic fluid from the distribution valve block ( 13 ). a system of fluid distribution pipes ( 19 ) is attached to the pick - up truck ( 1 ) and is routed from the distribution valve block ( 13 ) to a number of predetermined access points ( 16 )( 17 ). the fluid distribution pipes ( 19 ) are routed in pairs and terminate in standard detachable couplings ( 18 ) at the predetermined access points ( 16 )( 17 ). the distribution valve block ( 13 ) contains an switchable valve arrangement consisting of a number of electrically piloted valves that determine to which predetermined access points ( 16 )( 17 ) the proportional hydraulic flow is directed . additionally , the electrically piloted valves of the distribution valve block ( 13 ) also determine the directional state of each pair of fluid distribution pipes . each pair of fluid distribution pipes is configured with an a pipe and a b pipe and the distribution valve block ( 13 ) can direct that the high pressure hydraulic fluid is routed to either the a pipe or the b pipe with the other routed to the reservoir ( 14 ). referring to fig2 and 3 , a simple user interface module ( 30 ) is configured with an ergonomically designed handle ( 35 ), dead man trigger ( 39 ) and a simple bracket ( 36 ) that facilitates detachable mounting to the dash panel ( 41 ) of the pick - up truck ( 1 ) and also defeats the dead man trigger ( 39 ) when attached to the dash panel . the user interface module ( 30 ) contains a control joystick ( 31 ), a main power switch ( 32 ), an access point selector switch ( 33 ), a directional control switch ( 34 ), a control strategy selector switch ( 40 ) and a set - point button ( 37 ). an antenna ( 38 ) facilitates radio communication with the microprocessor control ( 12 ) so that command signals are transmitted between the user interface module ( 30 ) and microprocessor control ( 12 ) within a reasonable working range of the pick - up truck ( 1 ). fig4 illustrates the circuit diagram associated with the auxiliary hydraulic system previously described . the internal combustion engine ( 2 ) drives the multi - piston fluid pump ( 11 ) that draws its hydraulic supply from the reservoir ( 14 ) via a low pressure pipe ( 60 ) and provides hydraulic fluid under pressure to a supply pipe ( 61 ) that is directly connected to the distribution valve block ( 13 ). a filter ( 62 ) and bypass check valve ( 63 ) arrangement are provided in the low pressure pipe ( 60 ) to assure clean hydraulic fluid is supplied to the multi - piston fluid pump ( 11 ). a pressure relief valve ( 64 ) is configured to protect against inadvertent over loading of the system . the distribution valve block ( 13 ) contains two electrically piloted three way valves ( 70 )( 71 ), an overcentre valve ( 72 ), an internal high pressure manifold ( 73 ), an internal low pressure manifold ( 74 ) and two sets of fluid distribution pipe connections ( 75 )( 76 ). the supply pipe ( 61 ) is connected to the high pressure manifold ( 73 ) of the distribution valve block ( 13 ) and a return line ( 65 ) is adapted to connect to the low pressure manifold ( 74 ) of the distribution valve block ( 13 ). each fluid distribution pipe connection ( 75 )( 76 ) has an a port and a b port . the overcentre valve ( 72 ) is connected to the high pressure manifold ( 73 ) via an internal signal connection ( 77 ) so that the fluid flow in the low pressure manifold ( 74 ) is blocked unless the multi - piston fluid pump ( 11 ) is supplying the high pressure manifold ( 73 ). referring to both fig1 and 4 , the two electrically piloted three way valves ( 70 )( 71 ) are each configured with two electrical solenoid pilots ( 70 a )( 70 b )( 71 a )( 71 b ) which are connected to the appropriate power output stage of the microprocessor control ( 12 ) and allow selection of four operating states as follows : the first electrically piloted three way valve ( 70 ) is actuated to its first position via a signal to its first electrical solenoid pilot ( 70 a ) and the multi - piston fluid pump ( 11 ) supplies hydraulic fluid under pressure to port a of the first fluid distribution pipe connection ( 75 ) which is then routed via the fluid distribution pipes ( 19 ) to the a pipe of the rear predetermined access point ( 16 ). with the first electrically piloted three way valve ( 70 ) actuated to its first position via a signal to its first electrical solenoid pilot ( 70 a ), port b of the first fluid distribution pipe connection ( 75 ) is connected to the low pressure manifold ( 74 ) and then to the reservoir ( 14 ) via the overcentre valve ( 72 ) allowing a continuous fluid circuit to operate . the first electrically piloted three way valve ( 70 ) is actuated to its second position via a signal to its second electrical solenoid pilot ( 70 b ) and the multi - piston fluid pump ( 11 ) supplies hydraulic fluid under pressure to port b of the first fluid distribution pipe connection ( 75 ) which is then routed via the fluid distribution pipes ( 19 ) to the b pipe of the rear predetermined access point ( 16 ). with the first electrically piloted three way valve ( 70 ) actuated to its second position via a signal to its second electrical solenoid pilot ( 70 b ), port a of the first fluid distribution pipe connection ( 75 ) is connected to the low pressure manifold ( 74 ) and then to the reservoir ( 14 ) via the overcentre valve ( 72 ) allowing a continuous fluid circuit to operate . the second electrically piloted three way valve ( 71 ) is actuated to its first position via a signal to its first electrical solenoid pilot ( 71 a ) and the multi - piston fluid pump ( 11 ) supplies hydraulic fluid under pressure to port a of the second fluid distribution pipe connection ( 76 ) which is then routed via the fluid distribution pipes ( 19 ) to the a pipe of the front predetermined access point ( 17 ). with the second electrically piloted three way valve ( 71 ) actuated to its first position via a signal to its first electrical solenoid pilot ( 71 a ) port b of the second fluid distribution pipe connection ( 76 ) is connected to the low pressure manifold ( 74 ) and then to the reservoir ( 14 ) via the overcentre valve ( 72 ) allowing a continuous fluid circuit to operate . the second electrically piloted three way valve ( 71 ) is actuated to its second position via a signal to its second electrical solenoid pilot ( 71 b ) and the multi - piston fluid pump ( 11 ) supplies hydraulic fluid under pressure to port b of the second fluid distribution pipe connection ( 76 ) which is then routed via the fluid distribution pipes ( 19 ) to the b pipe of the front predetermined access point ( 17 ). with the second electrically piloted three way valve ( 71 ) actuated to its second position via a signal to its second electrical solenoid pilot ( 71 b ), port a of the second fluid distribution pipe connection ( 76 ) is connected to the low pressure manifold ( 74 ) and then to the reservoir ( 14 ) via the overcentre valve ( 72 ) allowing a continuous fluid circuit to operate . both of the two electrically piloted three way valves ( 70 )( 71 ) are configured to be closed centre so no hydraulic flow can occur through either valve when no pilot signal is applied . fig4 illustrates only two predetermined access point circuits and therefore only two electrically piloted three way valves ( 70 )( 71 ), but the distribution valve block ( 13 ) can be configured to supply multiple circuits with as many electrically piloted three way valves as are necessary . referring to fig1 , 2 and 4 , the microprocessor control ( 12 ) contains a high power digital processor , at least two power output stages configured to power both the electrically selectable poppet valves of the multi - piston fluid pump ( 11 ) and the electrically piloted three way valves of the distribution valve block ( 13 ), and a radio frequency interface with associated encoding and multiplexing to communicate with the user interface module ( 30 ). the digital processor is capable of interpreting command signals from the user interface module ( 30 ) and sending the appropriate output , via the power output stage , to the electrically selectable poppet valves of the multi - piston fluid pump ( 11 ) so as to provide real time , operator commanded control of proportional hydraulic flow . additionally , the digital processor is capable of interpreting command signals from the user interface module and sending the appropriate output , via the power output stage , to the electrically piloted three way valves of the distribution valve block ( 13 ) so as to direct hydraulic fluid flow to an operator commanded predetermined access point with an operator commanded flow direction . the selection of which electrically piloted three way valve ( 70 )( 71 ) will receive a signal from the first of the two power output stages is chosen via the access point selector switch ( 33 ) on the user interface module ( 30 ). the selection of which electrical solenoid pilot ( 70 a )( 70 b )( 71 a )( 71 b ) receives a signal from the first of the two power output stages is made via the control joystick ( 31 ) or the directional control switch ( 34 ) on the user interface module ( 30 ). additionally , the control joystick ( 31 ) also provides the demand signal to the second of the two power output stages of the microprocessor control ( 12 ) which in turn provides the appropriate output to the electrically selectable poppet valves of the multi - piston fluid pump ( 11 ) so as to provide real time , operator commanded control of proportional hydraulic flow . additionally , the digital processor of the microprocessor control ( 12 ) is capable of interpreting combined command signals from the user interface module ( 30 ) and inputs from selected remote sensors so as to undertake closed loop , real time control calculations so that commanded primary outputs such as hydraulic cylinder extension or hydraulic motor rotary speed can be maintained independently of outside influences such as the input speed of the multi - piston fluid pump ( 11 ). the microprocessor control ( 12 ) is configured so that only one of the electrically piloted three way valves ( 70 )( 71 ) can be selected at a time . fig5 illustrates an application of the auxiliary hydraulic system of the present invention in which a rotary mechanical power take off drive is provided by a low cost , positive displacement hydraulic motor ( 50 ) of standard configuration that uses rotors , gears , pistons or the like , detachably mounted to the vehicle structure via a mounting arrangement ( 51 ) that is configured to be compatible with the standard tow hitch receiver ( 52 ) of the vehicle . the positive displacement hydraulic motor ( 50 ) is provided with an output shaft ( 55 ) configured with an agricultural power take off standard 1⅜ inch diameter , six spline arrangement . the hydraulic motor ( 50 ) is connected to the a and b pipes of the rear predetermined access point ( 16 ) via flexible hoses ( 56 )( 57 ) and connectors compatible with the standard detachable couplings ( 18 ) of the auxiliary hydraulic system of the present invention . referring to fig1 and 5 , the motor additionally includes an integrated speed measurement device ( 58 ), such as a hall effect sensor , to provide information to the microprocessor control ( 12 ) so that appropriate real time , closed loop control of the electrically selectable poppet valves of the multi - piston fluid pump ( 11 ) can be undertaken to provide an appropriate hydraulic flow to achieve constant rotation speed of the output shaft ( 55 ) of the hydraulic motor ( 50 ) independently of the vehicle &# 39 ; s engine speed . in this manner , a power take off arrangement is provided that can operate at standard constant speeds , such as the agricultural requirement of 540 revolutions per minute , without operator intervention , while the vehicle &# 39 ; s engine speed is independently varied so as to provide rotary drive to implements such as hay bailers , snow blowers and the like . in a preferred embodiment of the microprocessor control ( 12 ), output flow is calculated directly from the duty cycle of the electrically selectable poppet valves and shaft speed of the multi - piston fluid pump ( 11 ) is instantaneously recorded when the set - point button ( 37 ) is activated on the user interface module ( 30 ). this combination of information is then utilized to set a target that maintains a constant output flow by varying the duty cycle of the electrically selectable poppet valves in response to changes in the vehicle &# 39 ; s engine speed . in this manner , set - point flow can be maintained without full closed loop feedback from the driven auxiliary equipment . fig6 illustrates a further application of the auxiliary hydraulic system of the present invention in which a wood splitter ( 90 ) has been adapted to be detachably mounted to the vehicle structure via a mounting arrangement ( 91 ) that is configured to be compatible with the standard tow hitch receiver ( 52 ) of the vehicle . the wood splitter ( 90 ) is provided with an actuation cylinder ( 95 ) that is connected to the a and b pipes of the rear predetermined access point ( 16 ) via flexible hoses ( 96 )( 97 ) and connectors compatible with the standard detachable couplings ( 18 ) of the auxiliary hydraulic system of the present invention . additionally referring to fig1 and 2 , when using the wood splitter the internal combustion engine ( 2 ) of the pick - up truck ( 1 ) is set at a high idle condition of approximately 1000 rpm with an automatic transmission set in park or a standard transmission in neutral with the emergency brake on . the user interface module ( 30 ) is detached from the dash panel and is utilized in a hand held mode by the user external to the pick - up truck ( 1 ). the rear predetermined access point ( 16 ) is chosen via the access point selector switch ( 33 ) on the user interface module ( 30 ) and the control joystick ( 31 ) is then used to choose the direction of movement of the actuation cylinder ( 95 ) of the wood splitter ( 90 ). the microprocessor control ( 12 ) will only provide command signals from its two power output stages when the dead man trigger ( 39 ) of the user interface module ( 30 ) is depressed . in this way , if the user interface module ( 30 ) is dropped then the auxiliary hydraulic system is shut down .
an auxiliary hydraulic system for vehicles , in particular pick - up trucks , is configured to supply hydraulic fluid under pressure to both on - board and off - board auxiliary equipment such as snow plows , dump boxes and wood splitters . the auxiliary hydraulic system includes a multi - piston fluid pump with electrically selectable poppet valves and an associated microprocessor control that facilitates variable output so that a desired proportional flow can be supplied to the auxiliary equipment . the system also provides a switchable valve arrangement for directional control and an arrangement of fluid distribution pipes and detachable couplings so that a range of different auxiliary equipment can be quickly and simply connected to the system . a simple user interface is also included so that the operator can command the auxiliary equipment from either within or in close proximity to the vehicle .