267B, 277B and 287B Multi Terrain Loaders Machine Systems Caterpillar

Illustration 1	g01114267
(1) Pilot operated hydraulic control ( work tool) (2) Ball valve for manually lowering the work tool (3) Control valve ( work tool) (4) Lift cylinders (5) Tilt cylinders (6) Auxiliary couplings (7) Return manifold (8) Hydraulic oil filter (9) Gear motor (fan drive) (10) Accumulator (11) Check valve (12) Gear motor (air conditioner) (13) Relief valve (charge oil) (14) Piston pump (hydrostatic system) (15) Speed sensing valve (16) Gear pump (17) hydraulic tank

Illustration 2	g01127138
(14) Piston pump hydrostatic system (16) Gear pump (17) Hydraulic tank

Gear pump (16) supplies the work tool hydraulic system with oil. Pump (16) is mounted to the front end of the piston pump for the hydrostatic system. Pump (16) is splined to the drive shaft of the piston pump for the hydrostatic system (14). The piston pump for the hydrostatic system is mounted to the engine. When the engine speed increases, the speed of pump (16) increases. This causes pump (16) to pump more oil to the work tool hydraulic system.

Illustration 3	g01064283

The first section of gear pump (16) continuously pumps oil through control valve (3). Control valve (3) is an open center control valve. The oil pressure for control valve (3) is regulated by a main relief valve that is installed in control valve (3). The main relief valve is set to a pressure of 23000 ± 700 kPa (3335 ± 100 psi).

The pilot oil for the work tool hydraulic system is supplied by the second section of pump (16). Oil flows out of the second section of pump (16) to the optional motor for the air conditioner (12). From the motor for the air conditioner, the oil flows to the fan drive motor (9). The oil flows through the fan drive motor to the oil filter (8). From the oil filter, the oil flows to the front section of the piston pump for the hydrostatic system (14). At the piston pump, the hydraulic oil flows passed the speed sensing valve (15). In order for the oil to flow to pilot valve (1), all three of the interlocks must be disengaged. In order for oil to flow to pilot valve (1), the hydraulic enable solenoid must be energized.

When the electrical requirements are complete, pilot oil will flow through check valve (11) to the accumulator (10). The pilot oil is used to charge the accumulator (10). The pilot oil will also flow to the pilot valve (1). When pilot valve (1) is activated, oil will be directed to control valve (3) in order to shift a control spool to the desired position. Once a control spool shifts, high pressure oil from pump (16) will flow to the selected work tool. Relief valve (13) maintains the pressure for the pilot oil system at 3800 ± 350 kPa (550 ± 50 psi) at engine high idle. The engine high idle speed is 2860 ± 50 rpm. Refer to the Systems Operation, "Pilot Hydraulic System" for additional information.

Hydraulic System for the Lift Arms Without the Diverter Valve (If Equipped)

Illustration 4	g01114277
(1) Pilot operated hydraulic control ( work tool) (2) Ball valve for manually lowering the work tool (3) Control valve ( work tool) (4) Lift cylinders (5) Tilt cylinders (6) Auxiliary couplings (7) Return manifold (8) Hydraulic oil filter (9) Gear motor (fan drive) (10) Accumulator (11) Check valve (12) Gear motor (air conditioner) (13) Relief valve (charge oil) (14) Piston pump (hydrostatic system) (15) Speed sensing valve (16) Gear pump (17) hydraulic tank

When the pilot operated hydraulic control ( work tool) (1) is moved to the RAISE position, pilot oil flows from the pilot operated hydraulic control (work tool) to the top side of the lift spool in the control valve ( work tool) (3). The spool moves down to the RAISE position. Hydraulic oil flows from the gear pump (16) through the lift spool and into the line for the head end of the lift cylinders (4). Near the lift cylinders, the single line splits into two branches. The two lines deliver hydraulic oil to the head end of both lift cylinders.

As the rods extend, oil is forced out of the rod end of the cylinders. The oil flows to the lift spool. Then, the oil flows through the lift spool to the tilt spool.

When the pilot operated hydraulic control ( work tool) (1) is moved to the LOWER position, pilot oil flows from the pilot operated hydraulic control (work tool) to the bottom of the lift spool in the control valve ( work tool) (3). The spool moves up to the LOWER position. Hydraulic oil flows from the gear pump (16) through the lift spool and into the line for the rod end of the lift cylinders (4). Near the lift cylinders, the single line splits into two branches. The two lines deliver hydraulic oil to the rod end of both lift cylinders.

As the rods retract, oil is forced out of the head end of the cylinders. The oil flows to the lift spool. Then, the oil flows through the lift spool to the tilt spool.

When the pilot operated hydraulic control is moved to the FLOAT position, pilot oil flows from the pilot operated hydraulic control (work tool) (1) to the bottom of the lift spool in the control valve ( work tool) (3). The lift spool is shifted upward to the FLOAT position by pilot oil. This position opens the rod ends of the lift cylinders and the head ends of the lift cylinders to the tank. The weight of the work tool will cause the work tool to lower to the ground. The work tool will then follow the contour of the ground. Supply oil from the gear pump can continue to flow to the tilt spool when the lift spool is in the FLOAT position.

The ball valve (2) is used for manual lowering of the lift arms. The ball valve allows oil to drain out of the head end of the cylinder. The hydraulic oil flow is directed to the return manifold (7). The ball valve should be used to lower the lift arms when the engine fails.

Hydraulic System for the Lift Arms with the Diverter Valve (If Equipped)

Illustration 5	g01114285
(1) Pilot operated hydraulic control ( work tool) (2) Diverter valve (3) Ball valve for manually lowering the work tool (4) Control valve ( work tool) (5) Lift cylinders (6) Tilt cylinders (7) Auxiliary couplings (8) Return manifold (9) Hydraulic oil filter (10) Gear motor (fan drive) (11) Accumulator (12) Check valve (13) Gear motor (air conditioner) (14) Relief valve (charge oil) (15) Piston pump (hydrostatic system) (16) Speed sensing valve (17) Gear pump (18) hydraulic tank

When the pilot operated hydraulic control ( work tool) (1) is moved to the RAISE position, the lift spool in the control valve ( work tool) (4) is shifted to the RAISE position by pilot oil. Hydraulic oil flows from the gear pump (17) through the lift spool and into the line for the head end of the lift cylinders (5). The oil from the rod end of the lift cylinders flows to the diverter valve (2). The pressure from the rod end of the lift cylinders is balanced with the pressure from the head end of the tilt cylinders. This causes the work tool to remain level while the lift arms are raised. From the diverter valve, the oil flows to the lift spool. The oil then flows to the tilt spool.

The diverter valve only affects the RAISE function. The LOWER function is not affected by the diverter valve.

In the LOWER position, oil flows from the spool to the diverter valve (2). From the diverter valve, the oil flows to the rod end of the cylinders. The oil pushes on the piston. The cylinders retract. Oil from the head end of the cylinders flows to the lift spool. Then, the oil flows to the tilt spool.

For information on the operation of the diverter valve, refer to the Systems Operation, "Diverter Valve".

The ball valve (3) is used for manual lowering of the lift arms. The ball valve allows oil to drain out of the head end of the lift cylinders. The hydraulic oil flow is directed to the return manifold (8). The ball valve should be used to lower the lift arms when the engine fails.

Tilt and Auxiliary Hydraulic System

Illustration 6	g01114286
(1) Pilot operated hydraulic control ( work tool) (2) Ball valve for manually lowering the work tool (3) Control valve ( work tool) (4) Lift cylinders (5) Tilt cylinders (6) Auxiliary couplings (7) Return manifold (8) Hydraulic oil filter (9) Gear motor (fan drive) (10) Accumulator (11) Check valve (12) Gear motor (air conditioner) (13) Relief valve (charge oil) (14) Piston pump (hydrostatic system) (15) Speed sensing valve (16) Gear pump (17) hydraulic tank (A) Couplings for circuit "A2" (B) Couplings for circuit "A2" (C) Solenoid for circuit "A2" (D) Solenoid for circuit "A1"

Hydraulic oil can be routed to the tilt cylinders (5) or hydraulic oil can be routed to the auxiliary circuit (6) .

The hydraulic oil is directed to the tilt spool in the control valve ( work tool) (3) by the pilot operated hydraulic control ( work tool) (1). The end of the spool that receives the pilot oil depends on the position of the pilot operated hydraulic control.

As the spool is shifted, hydraulic oil flows through the appropriate passages and into the appropriate line. Near the tilt cylinders (5), the single line splits into two branches. The two lines deliver hydraulic oil to both of the tilt cylinders.

If the machine is equipped with a diverter valve, the tilt cylinders will also be connected to the diverter valve. The diverter valve acts as a load leveler. The diverter valve is used only when the lift cylinders are being raised.

Illustration 7	g01064445
(18) Switch for the auxiliary hydraulic circuit

In order for the auxiliary circuit to activate, you must press the right side of switch (18). The ECM for the auxiliary hydraulic circuit activates solenoid (C) and solenoid (D) on the auxiliary spool.

Illustration 8	g01064450

Pilot oil is directed to the auxiliary circuit spool that is located in the control valve (3) by thumb wheel (19). Roll thumb wheel (19) upward in order to increase the flow of oil from the gear pump to coupling (B). Pilot oil moves the spool upward in order to allow more oil to flow through the spool to coupling (B) .

Roll the thumb wheel downward in order to increase the flow of hydraulic oil to coupling (A). Pilot oil moves the spool downward in order to allow more oil to flow from the gear pump through the spool to coupling (A).

For more information on the operation of the work tool hydraulic system and auxiliary hydraulic system, refer to the Systems Operation, "Control Valve (Work Tool)".

High Flow Auxiliary Circuit (If Equipped)

The High Flow XPS provides additional flow and additional pressure to the work tool hydraulic system. The High Flow XPS is available on 287B machines.

Illustration 9	g01133808
Schematic for the piston pump (auxiliary)

The piston pump (auxiliary) is among the features in the High Flow XPS system. The piston pump (auxiliary) is a variable displacement pump. The piston pump (auxiliary) is mounted to the A22 piston pump. The gear pump for the work tool hydraulic system is mounted to the piston pump (auxiliary).

In order to engage the High Flow XPS, the following conditions must exist:

• The ECM must be flashed with the appropriate software. The 254-9215 Work Tool Software Gp (1) is the latest release.

• The correct model of machine must be configured in ET.

• The 224-0744 Pressure Switch (2) must be installed in connector RA-C3 on the harness for the right joystick control.

• When you utilize an "A-Series" work tool or a "B-Series" work tool without an electrical harness, the 241-3763 Plug As (Jumper) (3) must be inserted into the work tool harness. An "A-Series" work tool that utilizes an electrical harness must use the 225-8014 Work Tool Harness As (4) in order to connect to the work tool harness on the lift arm.

• The rocker switch for the Auxiliary Hydraulic Mode must be activated by pressing the left side of the switch.

• The thumb wheel that is located on the right joystick must be rolled to the position of full actuation. This hydraulic function only engages at full actuation of the thumb wheel.