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| Illustration 1 | g01392385 |
(1) Displacement piston cavity (2) Port "6" (hydraulic tank) (3) Bias piston cavity (4) Left tow point control cylinder (5) Left hopper hoist cylinder (6) Right tow point control cylinder (7) Right hopper hoist cylinder (8) Truck hitch cylinders (9) Flow compensator spool (10) Auxiliary pump (11) Left tow point control valve (12) Pressure reducing valve (13) Hopper lower valve (14) Hopper raise valve (15) Right two point control valve (16) Pressure reducing valve (17) Hopper lower valve (18) Hopper raise valve (19) To forward return manifold (20) Pressure reducing valve (21) Truck hitch control valves (22) Auxiliary pressure manifold (23) Right auger hoist cylinder (24) Left auger hoist cylinder (25) Left shift cylinder (26) Right shift cylinder (27) Left brake cylinder (28) Right brake cylinder (29) Needle valve (30) Hand pump (31) Brake release manifold (32) Left screed hoist cylinder (33) Right screed hoist cylinder (34) Left apron fold cylinder (35) Right apron fold cylinder (36) Screed extension manifold (37) To screed vibratory return (38) Left screed extension cylinder (39) Right screed extension cylinder (40) Ventilation motor (41) To hydraulic tank in return filter (42) Ventilation motor flow control valve (43) Ventilation shutoff valve (44) Pressure (45) Tank (46) Auger lift valve (47) Auger lower valve (48) Pressure reducing valve (49) Shift valve (50) Parking brake valve (51) Screed float valve (52) Screed lift valve (53) Pressure reducing valve (54) Screed assist valve (55) Apron lower valve (56) Apron raise valve (57) Gauge (58) To return filter | |
When the auxiliary hydraulic pump is at rest, the swashplate spring forces the swashplate to the maximum angle. When the engine is started, the auxiliary hydraulic pump generates flow.
Pump supply oil acts on the pressure compensator spool. Supply oil acts against the force of the spring. System pressure causes the pressure compensator spool to shift. This shift directs oil into the displacement piston cavity.
Pressure in the displacement piston cavity works against the bias spring. As the pressure increases in the displacement cavity, the displacement piston moves the swashplate toward a minimum angle. As the swashplate angle decreases, the displacement piston uncovers a passage. This passage allows oil to flow from the displacement piston cavity into the pump case.
At this point, supply pressure decreases. The force from the pressure compensator spring causes the pressure compensator spool to shift. This shift opens the displacement piston cavity to the pump case drain. In this case, the bias spring causes the swashplate angle to increase.
As the swashplate angle increases, the pressure in the system will increase. The pressure compensator spool senses the increase in pressure. The pressure compensator spool shifts, and supply oil is directed into the displacement piston cavity. Eventually, the pressure compensator spool and the bias spring reach equilibrium. In this state, the auxiliary hydraulic pump generates just enough flow in order to maintain the pressure in the system to a pressure of 13780 ± 172 kPa (2000 ± 25 psi).
Output from the auxiliary pump is sent to the following places: the pressure manifold, the screed extension manifold and the auxiliary control manifold. The pressure manifold distributes oil to the following places: the left tow point pressure reducing valve, the right tow point pressure reducing valve and the truck hitch manifold. All valves in the auxiliary hydraulic system are closed centered.
Note: The pressure reducing valve in the left and right tow point manifold limits the pressure in the tow point solenoids to 6900 ± 350 kPa (1000 ± 50 psi).
The auxiliary manifold supplies oil to a flow control valve that is rated at 9.8 L (2.6 US gal). This valve is located in the passage to the ventilation motor. The flow control valve maintains the flow to the ventilation motor at a constant rate. The line to the ventilation motor contains a shutoff valve. When this valve is closed, the ventilation motor does not operate.
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| Illustration 2 | g01392391 |
(1) Displacement piston cavity (2) Port "6" (hydraulic tank) (3) Bias piston cavity (4) Left tow point control cylinder (5) Left hopper hoist cylinder (6) Right tow point control cylinder (7) Right hopper hoist cylinder (8) Truck hitch cylinders (9) Flow compensator spool (10) Auxiliary pump (11) Left tow point control valve (12) Pressure reducing valve (13) Hopper lower valve (14) Hopper raise valve (15) Right two point control valve (16) Pressure reducing valve (17) Hopper lower valve (18) Hopper raise valve (19) To forward return manifold (20) Pressure reducing valve (21) Truck hitch control valves (22) Auxiliary pressure manifold (23) Right auger hoist cylinder (24) Left auger hoist cylinder (25) Left shift cylinder (26) Right shift cylinder (27) Left brake cylinder (28) Right brake cylinder (29) Needle valve (30) Hand pump (31) Brake release manifold (32) Left screed hoist cylinder (33) Right screed hoist cylinder (34) Left apron fold cylinder (35) Right apron fold cylinder (36) Screed extension manifold (37) To screed vibratory return (38) Left screed extension cylinder (39) Right screed extension cylinder (40) Ventilation motor (41) To hydraulic tank in return filter (42) Ventilation motor flow control valve (43) Ventilation shutoff valve (44) Pressure (45) Tank (46) Auger lift valve (47) Auger lower valve (48) Pressure reducing valve (49) Shift valve (50) Parking brake valve (51) Screed float valve (52) Screed lift valve (53) Pressure reducing valve (54) Screed assist valve (55) Apron lower valve (56) Apron raise valve (57) Gauge (58) To return filter | |
This schematic shows the auxiliary hydraulic system in the following conditions:
- Tow points (INCREASE)
- Truck hitch (OPEN)
- Screed extensions (EXTEND)
- Screed (LIFT)
- Auger (LIFT)
- Hopper (LIFT)
- Speed range (TRAVEL)
- Parking brake (RELEASED)
- Apron fold (RAISE)
Note: During normal operation, these conditions would not simultaneously occur. The circuit is shown under these conditions for illustration purposes only.
When an active left tow point switch is in the INCREASE position, the left tow point raise solenoid is energized. The left tow point control valve directs oil to the counterbalance valve. The counterbalance valve consists of two check valves and two spools.
Oil flows through the check valve of the counterbalance valve and into the head end of the left tow point cylinder. The cylinder begins to extend. This extension displaces oil from the rod end of the cylinder. Displaced oil from the rod end of the cylinder flows to the return side of the counterbalance valve. Initially, the counterbalance valve blocks the return oil. As the pressure in the line to the head end of the tow point cylinder increases, the spool in the line to the rod end of the cylinder shifts. This shift opens a passage which allows return oil from the rod end of the cylinder to flow into the return filter in the hydraulic tank.
Note: The right tow point system follows the same principles of operation as the left.
At the truck hitch manifold, pump supply oil flows through a pressure reducing valve. This valve limits the downstream pressure to 6900 ± 350 kPa (1000 ± 50 psi). When the active truck hitch switch is in the OPEN position, the truck hitch open solenoid is energized. The truck hitch control valve opens a passage which allows the reduced supply oil to act against the pilot opened check valve. The check valve opens, and supply oil flows to the head ends of the truck hitch cylinders. Return oil from the rod ends of the cylinders flows in the following places: through the pilot opened check valve, across the truck hitch control valve and to the return filter in the hydraulic tank.
When an active left screed extension switch is in the EXTEND position, the left screed extend solenoid is energized. The screed extend control valve opens a passage which allows the pump supply oil to act against the pilot opened check valve. The check valve opens, and supply oil flows to the head end of the left screed extend cylinder. Return oil from the rod end of the cylinder flows in the following places: through the pilot opened check valve, across the screed extend control valve and to the return line in the auxiliary manifold.
Note: The right screed extension system follows the same principles of operation as the left.
When the active screed lift switch is in the LIFT position, the screed lift solenoid is energized. Pump supply oil flows across the screed lift valve, through the pilot opened check valve, and into the rod ends of the screed hoist cylinders. As the screed hoist cylinders retract, displaced oil from the head ends of the cylinders is sent into the return line in the auxiliary manifold.
When the active auger lift switch is in the LIFT position, the auger lift solenoid is energized. Pump supply oil flows across the auger lift valve to the pilot opened check valves. Supply oil flows through the pilot opened check valve which is in the line to the rod end of the right auger hoist cylinder. Supply oil opens the pilot opened check valve which is in the line to the head end of the left auger hoist cylinder.
As supply oil flows into the rod end of the right auger hoist cylinder, the cylinder retracts. Cylinder movement displaces oil from the head end of the right auger hoist cylinder. The displaced oil is directed into the rod end of the left auger hoist cylinder. This action causes the left cylinder to retract. Displaced oil from the head end of the left auger hoist cylinder flows in the following places: through the pilot opened check valve, across the auger lower valve and into the auxiliary manifold return line.
When the active hopper control switch is in the LIFT position, the right hopper raise solenoid and the left hopper raise solenoid are energized. Pump supply oil flows across the hopper raise valves to the pilot opened check valves. Supply oil flows through the pilot opened check valves in the line to the rod end of the right hopper hoist cylinders and the rod end of the left hopper hoist cylinder. Supply oil opens the pilot opened check valves in the line to the head ends of the cylinders. After the supply oil leaves the hopper manifold, oil is directed through an orifice and into the head end of the hopper hoist cylinders.
As the hopper hoist cylinders retract, oil which was from the head ends of the cylinders flows back to the hopper manifold. Inside the manifold, return oil flows in the following places: through the pilot opened check valve, across the hopper lower valve and into the auxiliary manifold return line. Orifices that are located in the line to the rod ends of the hopper hoist cylinders limit the speed of raising the hopper.
When the active propulsion mode switch is in the TRAVEL position, the shift solenoid is energized. Refer to Specifications, Systems Operation/Testing and Adjusting, KENR5727 for details about this electrical circuit. The pressure reducing valve which is upstream from the shift valve in the auxiliary manifold reduces the downstream pressure to 4800 ± 350 kPa (700 ± 50 psi). The reduced pressure oil flows across the shift valve. The oil also flows into the right shift cylinder and into the left shift cylinder. This causes the machine to operate in the travel speed range.
When both parking brake switches are in the OFF position and all other brake release parameters are met, the parking brake solenoid is energized. Under these conditions, pump supply oil flows across the parking brake valve to the brake release manifold. When the needle valve which is inside the brake release manifold is open, supply oil flows out of the brake release manifold to the right brake cylinder and to the left brake cylinder.
Note: When the needle valve which is in the brake release manifold is closed, the hand pump can be used in order to manually release the parking brakes.
When the active apron fold control switch is in the UP position, the apron raise solenoids are energized. Pump supply oil flows across the apron raise valve to the pilot opened check valves. Supply oil opens the pilot opened check valve which is in the line to the head end of the cylinders. After the supply oil leaves the apron manifold, the flow is split into two streams. One stream leads to the head end of the left apron raise cylinder. The other stream leads to the head end of the right apron raise cylinder.
As the apron raise cylinders extend, displaced oil from the rod ends of the cylinders flows back to the apron manifold. Inside the manifold, return oil flows in the following places: through the pilot opened check valve, across the apron lower valve and into the auxiliary manifold return line.
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| Illustration 3 | g01392401 |
(1) Displacement piston cavity (2) Port "6" (hydraulic tank) (3) Bias piston cavity (4) Left tow point control cylinder (5) Left hopper hoist cylinder (6) Right tow point control cylinder (7) Right hopper hoist cylinder (8) Truck hitch cylinders (9) Flow compensator spool (10) Auxiliary pump (11) Left tow point control valve (12) Pressure reducing valve (13) Hopper lower valve (14) Hopper raise valve (15) Right two point control valve (16) Pressure reducing valve (17) Hopper lower valve (18) Hopper raise valve (19) To forward return manifold (20) Pressure reducing valve (21) Truck hitch control valves (22) Auxiliary pressure manifold (23) Right auger hoist cylinder (24) Left auger hoist cylinder (25) Left shift cylinder (26) Right shift cylinder (27) Left brake cylinder (28) Right brake cylinder (29) Needle valve (30) Hand pump (31) Brake release manifold (32) Left screed hoist cylinder (33) Right screed hoist cylinder (34) Left apron fold cylinder (35) Right apron fold cylinder (36) Screed extension manifold (37) To screed vibratory return (38) Left screed extension cylinder (39) Right screed extension cylinder (40) Ventilation motor (41) To hydraulic tank in return filter (42) Ventilation motor flow control valve (43) Ventilation shutoff valve (44) Pressure (45) Tank (46) Auger lift valve (47) Auger lower valve (48) Pressure reducing valve (49) Shift valve (50) Parking brake valve (51) Screed float valve (52) Screed lift valve (53) Pressure reducing valve (54) Screed assist valve (55) Apron lower valve (56) Apron raise valve (57) Gauge (58) To return filter | |
This schematic shows the auxiliary hydraulic system in the following conditions:
- Tow points (DECREASE)
- Truck hitch (CLOSE)
- Screed extensions (RETRACT)
- Screed (FLOAT)
- Auger (LOWER)
- Hopper (LOWER)
- Speed range (PAVE)
- Apron fold (LOWER)
- Parking brake (RELEASED)
Note: During normal operation, these conditions would not simultaneously occur. The circuit is shown under these conditions for illustration purposes only.
When an active left tow point switch is in the DECREASE position, the left tow point lower solenoid is energized. The left tow point control valve directs oil to the counterbalance valve. The counterbalance valve consists of two check valves and two spools.
Oil flows through the check valve of the counterbalance valve and flows into the rod end of the left tow point cylinder. The cylinder begins to retract. This retraction displaces oil from the head end of the cylinder. Displaced oil from the head end of the cylinder flows to the return side of the counterbalance valve. Initially, the counterbalance valve blocks the return oil. As the pressure in the line to the rod end of the tow point cylinder increases, the spool in the line to the head end of the cylinder shifts. This shift opens a passage which allows return oil from the head end of the cylinder to flow to the return filter in the hydraulic tank.
Note: The right tow point system follows the same principles of operation as the left.
At the truck hitch manifold, pump supply oil flows through a pressure reducing valve. This valve limits the downstream pressure to 6900 ± 170 kPa (1000 ± 25 psi). When the active truck hitch switch is in the CLOSE position, the truck hitch close solenoid is energized. The truck hitch control valve opens a passage which allows the reduced supply oil to act against the pilot opened check valve. The check valve opens, and supply oil flows to the rod ends of the truck hitch cylinders. Return oil from the head ends of the cylinders flows in the following places: through the pilot opened check valve, across the truck hitch control valve and to the return filter in the hydraulic tank.
When an active left screed extension switch is in the RETRACT position, the left screed retract solenoid is energized. The screed extend control valve opens a passage which allows the pump supply oil to act against the pilot opened check valve. The check valve opens, and supply oil flows to the rod end of the left screed extend cylinder. Return oil from the head end of the cylinder flows in the following places: through the pilot opened check valve, across the screed extend control valve and to the return line in the auxiliary manifold.
Note: The right screed extension system follows the same principles of operation as the left.
When all the screed lift switches are in the FLOAT position, and the screed counterbalance switch is in the OFF position, the screed lower solenoid is energized. Under these conditions, the rod ends of the screed hoist cylinders are open to the return line in the auxiliary manifold.
Gravity causes the screed to lower, and oil is displaced from the rod ends of the screed hoist cylinders. Orifices in the lines to the rod ends of the cylinders limit the speed of lowering the screed. As oil is displaced from the rod ends of the screed hoist cylinders, a vacuum is created in the head ends of the cylinders. This vacuum draws oil from the hydraulic tank in order to fill the void in the head ends of the cylinders.
When the active auger lift switch is in the LIFT position, the auger lift solenoid is energized. Pump supply oil flows across the auger lift valve to the pilot opened check valves. Supply oil flows through the pilot opened check valve in the line to the rod end of the right auger hoist cylinder. Supply oil opens the pilot opened check valve which is in the line to the head end of the left auger hoist cylinder.
As supply oil flows into the rod end of the right auger hoist cylinder, the cylinder retracts. Cylinder movement displaces oil from the head end of the right auger hoist cylinder. The displaced oil is directed into the rod end of the left auger hoist cylinder. This action causes the right cylinder to retract. Displaced oil from the head end of the left auger hoist cylinder flows in the following places: through the pilot opened check valve, across the auger lift valve and into the auxiliary manifold return line.
When the active hopper control switch is in the LOWER position, the right hopper lower solenoid and the left hopper lower solenoid are energized. Pump supply oil flows across the hopper lower valves to the pilot opened check valves. Supply oil flows through the pilot opened check valves in the line to the head end of the right hopper hoist cylinders and the left hopper hoist cylinder. Supply oil opens the pilot opened check valves in the line to the rod ends of the cylinders. After the supply oil leaves the hopper manifold, oil is directed into the head end of the hopper hoist cylinders.
As the hopper hoist cylinders extend, oil which was from the rod ends of the cylinders flows back to the hopper manifold. Inside the manifold, return oil flows in the following places: through the pilot opened check valve, across the hopper raise valve and into the auxiliary manifold return line. Orifices in the line to the rod ends of the hopper hoist cylinders limit the speed of lowering the hopper.
When the active apron fold control switch is in the DOWN position, the apron lower solenoids are energized. Pump supply oil flows across the apron lower valve to the pilot opened check valves. Supply oil opens the pilot opened check valve which is in the line to the rod end of the cylinders. After the supply oil leaves the apron manifold, the flow is split into two streams. One stream leads to the rod end of the left apron raise cylinder. The other stream leads to the rod end of the right apron raise cylinder.
As the apron lower cylinders retract, displaced oil from the head ends of the cylinders flows back to the apron manifold. Inside the manifold, return oil flows in the following places: through the pilot opened check valve, across the apron raise valve and into the auxiliary manifold return line.
When the active propulsion mode switch is in the PAVE position, the shift solenoid is de-energized. In this case, the right shift cylinder and the left shift cylinder are open to the return line. As a result, the machine will operate in the pave speed range.
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| Illustration 4 | g01392406 |
(1) Displacement piston cavity (2) Port "6" (hydraulic tank) (3) Bias piston cavity (4) Left tow point control cylinder (5) Left hopper hoist cylinder (6) Right tow point control cylinder (7) Right hopper hoist cylinder (8) Truck hitch cylinders (9) Flow compensator spool (10) Auxiliary pump (11) Left tow point control valve (12) Pressure reducing valve (13) Hopper lower valve (14) Hopper raise valve (15) Right two point control valve (16) Pressure reducing valve (17) Hopper lower valve (18) Hopper raise valve (19) To forward return manifold (20) Pressure reducing valve (21) Truck hitch control valves (22) Auxiliary pressure manifold (23) Right auger hoist cylinder (24) Left auger hoist cylinder (25) Left shift cylinder (26) Right shift cylinder (27) Left brake cylinder (28) Right brake cylinder (29) Needle valve (30) Hand pump (31) Brake release manifold (32) Left screed hoist cylinder (33) Right screed hoist cylinder (34) Left apron fold cylinder (35) Right apron fold cylinder (36) Screed extension manifold (37) To screed vibratory return (38) Left screed extension cylinder (39) Right screed extension cylinder (40) Ventilation motor (41) To hydraulic tank in return filter (42) Ventilation motor flow control valve (43) Ventilation shutoff valve (44) Pressure (45) Tank (46) Auger lift valve (47) Auger lower valve (48) Pressure reducing valve (49) Shift valve (50) Parking brake valve (51) Screed float valve (52) Screed lift valve (53) Pressure reducing valve (54) Screed assist valve (55) Apron lower valve (56) Apron raise valve (57) Gauge (58) To return filter | |
The pressure reducing valve for the screed counterbalance system reduces the pressure which is available to the screed assist solenoid. When both screed lift switches are in the FLOAT position and the screed counterbalance switch is in the ON position, the screed assist solenoid is energized, and the screed float solenoid is de-energized.
When the screed assist solenoid is energized, reduced pressure oil flows to the rod ends of the screed hoist cylinders. This oil provides a lift to the screed. This action reduces the force that the screed exerts against the asphalt mat.
The pressure reducing valve setting can be adjusted. The setting is shown on the gauge which is attached to port "G2" of the auxiliary control manifold. The higher the pressure setting of the pressure reducing valve, the greater the lift that is provided to the screed. The maximum screed assist pressure should be approximately 520 kPa (75 psi).