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| Illustration 1 | g00823269 |
(1) Pilot operated hydraulic control ( hydrostatic) (2) Pilot operated hydraulic control ( work tool) (3) Bank valve (4) Interlock manifold valve (5) Left piston motor ( hydrostatic) (6) Right piston motor ( hydrostatic) (7) Return manifold (8) Oil filter (9) Gear motor (fan drive) (10) Radiator and hydraulic oil cooler (11) Piston pump ( hydrostatic) (12) Gear pump (13) Hydraulic tank | |
The 216 and 226 Skid Steer Loaders consist of a hydrostatic drive system, a work tool hydraulic system and a pilot hydraulic system. The hydrostatic drive system and the work tool hydraulic system are controlled by the pilot system.
The three systems use one common tank (13). The piston pump ( hydrostatic) (11) and the gear pump (12) are splined to the engine. The piston pump provides flow for the hydrostatic drive system. The gear pump provides flow for the work tool system. The gear pump also provides charge oil for the hydrostatic system, and oil for the pilot system. The oil that flows toward the piston pump from the gear pump is filtered through the oil filter (8). The gear motor (fan drive) (9) receives oil flow just before the oil filter. The oil flow that goes to the work tool system is not filtered by the oil filter.
The pilot operated hydraulic controls (1) and (2) are supplied with oil by the gear pump. The pilot operated hydraulic controls are used to route signal oil to the piston pump and pilot oil to the bank valve (3). The signal oil moves the swashplates in the piston pump in order to control the piston motors ( hydrostatic). The pilot oil shifts the spools in the bank valve in order to control the work tool.
Oil returns to the return manifold (7) from the following components: the pilot operated hydraulic controls, the piston pump, interlock manifold valve (4) and the piston motors (5) and (6). The oil can flow to the oil cooler (9) and to the tank (13) from the return manifold. Oil that is returning from the bank valve flows directly to the tank.
Hydraulic Supply System
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| Illustration 2 | g00823269 |
(1) Pilot operated hydraulic control ( hydrostatic) (2) Pilot operated hydraulic control ( work tool) (3) Bank valve (4) Interlock manifold valve (5) Left piston motor ( hydrostatic) (6) Right piston motor ( hydrostatic) (7) Return manifold (8) Oil filter (9) Gear motor (fan drive) (10) Radiator and hydraulic oil cooler (11) Piston pump ( hydrostatic) (12) Gear pump (13) Hydraulic tank | |
The hydraulic oil tank (13) stores the hydraulic oil for the machine. The hydraulic tank supplies oil to the hydrostatic system, the work tool hydraulic system, and the pilot hydraulic system.
A strainer is located inside the oil tank on the end of the supply line. The tank is not pressurized. A hose connects the tank to a breather.
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| Illustration 3 | g00823339 |
(14) Hydraulic tank filler cap (15) Hydraulic tank sight gauge | |
The sight gauge (15) is located on the right side of the machine below the filler cap (14). Maintain the oil level approximately in the middle of the sight gauge. Refer to the Operation and Maintenance Manual, SEBU7468, "Hydraulic System Oil Level - Check" for more information.
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| Illustration 4 | g00823341 |
(13) Hydraulic tank (14) Filler cap (16) Oil temperature sender | |
An oil temperature sender (16) is located on the bottom of the hydraulic tank (13). When the hydraulic oil temperature exceeds 102° ± 3°C (216° ± 5°F), the sender will activate the indicator light that is located on the left control panel. When the hydraulic oil temperature cools to a minimum temperature of 90 °C (194 °F), the sender will deactivate the indicator light.
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| Illustration 5 | g00823340 |
Hydraulic oil from hydraulic tank (13) flows into gear pump (12). The gear pump is driven by a common drive shaft that runs through the piston pump ( hydrostatic) (11). The gear pump supplies oil to the hydraulic system and to the hydrostatic system.
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| Illustration 6 | g00823358 |
(9) Gear motor (fan drive) (17) Check valve | |
The gear motor (fan drive) (9) provides cooling air for the radiator and hydraulic oil cooler. Hydraulic oil then flows out of the gear motor and into the oil filter (8) .
Hydraulic oil for the gear motor is supplied by the gear pump. Hydraulic oil from the tank flows to the front section of the gear pump. The oil flows from the gear pump to the gear motor.
The flow of oil through the gear motor turns the fan that cools the hydraulic oil that passes through the oil cooler. The fan motor will rotate in direct relation to the amount of hydraulic oil flow until the hydraulic oil pressure reaches the setting for the relief valve. The relief valve allows the excess oil to bypass the gear motor. The relief valve is set to 4300 kPa (625 psi). The fan cools the coolant that flows through the radiator and the fan cools the oil that flows through the oil cooler.
The check valve (17) allows the gear motor to spin freely after the engine is turned off.
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| Illustration 7 | g00823365 |
(8) Oil filter (18) Fill port (19) Test port | |
Hydraulic oil flows out of the gear motor (fan drive) and into the hydraulic oil filter (8). The oil filter is a five micron filter. From the oil filter, the hydraulic oil flows to the piston pump ( hydrostatic).
The hydraulic oil filter serves the purpose of removing any particles that could damage the piston pump. The hydraulic oil then flows into the front section of the piston pump.
The port (18) is used to test for contaminants in the hydraulic oil. For more information on the oil sample port, refer to Hydraulic System Testing and Adjusting, RENR2860, "Hydraulic Oil Contamination Test". The port is also used to pump oil into the piston pump. For more information on the fill port, refer to Hydraulic System Testing and Adjusting, RENR2860, "Filling and Flushing the Hydrostatic System Test".
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| Illustration 8 | g00823370 |
(8) Oil filter (18) Test port (19) Fill port (20) Oil filter bypass valve | |
The oil filter bypass valve (20) opens when a differential pressure of 200 kPa (30 psi) is reached. An indicator will light on the right control panel when the differential pressure reaches 172 kPa (25 psi). For more information about the alert indicators, refer to the Operation and Maintenance Manual, SEBU7468, "Alert Indicators".
Interlock System
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| Illustration 9 | g00823373 |
(1) Pilot operated hydraulic control ( hydrostatic) (2) Pilot operated hydraulic control ( work tool) (3) Bank valve (4) Interlock manifold valve (5) Left Piston motor ( hydrostatic) (6) Right Piston motor ( hydrostatic) (7) Return manifold (11) Piston pump ( hydrostatic) (12) Gear pump (13) Hydraulic tank (21) Solenoid valve ( hydrostatic) (22) Solenoid valve ( parking brake) (23) Solenoid valve ( work tool) (24) Modulating valve ( auxiliary) (25) Modulating valve ( auxiliary) | |
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| Illustration 10 | g00823399 |
(21) Solenoid valve ( hydrostatic) (22) Solenoid valve ( parking brake) (23) Solenoid valve ( work tool) (24) Modulating valve ( auxiliary) (25) Modulating valve ( auxiliary) | |
There are five solenoid valves for the interlock system on the Skid Steer Loader. The interlock solenoids include the following solenoids: the solenoid valve ( hydrostatic) (21), the solenoid valve ( parking brake) (22), the solenoid valve ( work tool) (23) and modulating valves ( auxiliary) (24) and (25). The solenoid valve ( hydrostatic), the solenoid valve ( parking brake), and the solenoid valve ( work tool) are energized under the following conditions:
- The seat must be occupied.
- The arm bar must be in the DOWN position.
- The parking brake switch must be disengaged.
All of the interlock solenoids are located on the interlock manifold valve (4). The modulating valves ( auxiliary) are optional equipment.
The solenoid valve ( hydrostatic) (21) allows the flow of hydraulic signal oil to the pilot operated hydraulic control (1). When the solenoid is de-energized, no hydraulic signal oil flows to the hydraulic control.
The solenoid valve ( parking brake) (23) allows the flow of pilot hydraulic oil to the brakes. The parking brakes are located on piston motors (4) and (5) .
When the solenoid is de-energized, the flow of pilot hydraulic oil is blocked. Hydraulic oil from the motors drains through the solenoid valve to the tank. This allows the spring force to overcome the oil pressure which engages the brakes. When the solenoid is energized, pilot hydraulic oil flows into the parking brakes. When pressure is built up in order to overcome the spring pressure, the brakes will disengage.
The solenoid valve ( work tool) (20) allows the flow of pilot hydraulic oil to the pilot operated hydraulic control (2). When the solenoid is de-energized no flow of pilot hydraulic oil reaches the hydraulic control.
The modulating valves ( auxiliary) are optional equipment. The modulating valves ( auxiliary) (24) and (25) are electronically activated by the auxiliary circuit switch that is located on the pilot operated hydraulic control ( work tool). The valves enable the flow of pilot hydraulic oil to the auxiliary control valve in the bank valve (3) .
The gear pump (12) supplies the hydraulic oil flow for the pilot system and the brake system. After the oil flows through the speed sensing valve in the piston pump ( hydrostatic) (11), the signal oil and the pilot oil to the pilot operated hydraulic controls should be proportional to the engine rpm.
Return Manifold System
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| Illustration 11 | g00823401 |
(1) Pilot operated hydraulic control ( hydrostatic) (2) Pilot operated hydraulic control ( work tool) (3) Bank valve (4) Interlock manifold valve (5) Left Piston motor ( hydrostatic) (6) Right Piston motor( hydrostatic) (7) Return manifold (11) Piston pump (12) Gear pump (13) Hydraulic tank | |
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| Illustration 12 | g00823404 |
(7) Return manifold (26) Oil cooler bypass valve (27) Hydraulic drain valve | |
Oil flows to the return manifold (7) from the following components: the pilot operated hydraulic controls (1) and (2), the piston pump (11) and the piston motors (5) and (6) .
The return manifold provides hydraulic oil to the oil cooler in order to keep the oil from getting too hot.
The fan blows air across the oil cooler. The air cools the hydraulic oil. The hydraulic oil then returns to the return manifold. A bypass check valve (26) is located in the return manifold. The bypass check valve prevents high pressure oil from entering the oil cooler when the machine is started. The bypass check valve opens when the pressure in the cooler exceeds 172 kPa (25 psi). From the return manifold, hydraulic oil drains back to the hydraulic tank.
The valve (27) on the return manifold (7) is used to drain the tank. A hose connects to the valve.