Steering, Fan, and Leveling Blade Hydraulic System
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| Illustration 1 | g00949249 |
Hydraulic Block Diagram (1) Steering pump (charge) (2) Sump (3) Priority valve (4) Relief valve (steering pump) (5) Relief valve (fan motor) (6) Fan motor (7) Control valve (blade) (8) Hydraulic cylinder (blade) (9) Control spool (blade) (10) Relief valve (blade) (11) Relief valve (blade) (12) Hydraulic cylinder (steering) (13) Hydraulic cylinder (steering) (14) Metering pump (15) Line to propel filter (AA) System pressure (AB) Charge pressure (AC) Sump (AD) Activated components (AE) Load sense (AD) First pressure reduction (load sense) | |
The steering, fan, and leveling blade system contains the following main components:
- Steering pump (1) (charge)
- Fan motor (6)
- Control valve (7) (blade)
- Hydraulic cylinder (8) (blade)
- Hydraulic cylinder (12) (steering)
- Hydraulic cylinder (13) (steering)
- Metering pump (14)
Steering pump (1) delivers oil to all of the main components in the steering, fan, and leveling blade system. Typically, the requirements of the oil flow for the steering circuit are significantly less than the available pump flow. Priority valve (3) will direct most of the oil flow to the steering system during extreme steering input. This oil flow is usually for short durations. The fan motor and the leveling blade system will slow down under intensive turning situations. The total oil flow to the charge system should be consistent at all times. Relief valve (4) limits the maximum oil pressure in this system to the relief valve setting.
The steering system is a load sensing system. Hydraulic oil for the steering circuit is supplied by steering pump (1). Priority valve (3) is part of the steering pump. This valve gives priority to the steering circuit. The priority valve senses pressure in the steering circuit. As a result, oil flow will be divided between the steering system and fan motor (6). The amount of oil flow that is delivered to the fan motor is determined by the input to the steering system. When the steering wheel is not being turned, the priority valve will direct all of the oil flow to the fan motor and control valve (7) (blade).
Systems Operation for Straight Travel and Blade Hold
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| Illustration 2 | g00939553 |
Hydraulic Schematic (1) Steering pump (charge) (3) Priority valve (steering pump) (6) Fan motor (8) Hydraulic cylinder (blade) (9) Control spool (blade) (12) Hydraulic cylinder (steering) (13) Hydraulic cylinder (steering) (16) Line to the propel filter (18) Valve envelope (priority valve) (21) Valve envelope (priority valve) (22) Valve envelope (metering pump) (23) Valve envelope (blade) (24) Hydraulic line (blade) (25) Hydraulic line (fan motor) (26) Hydraulic line (27) Hydraulic line (28) Pilot (14) Metering pump (AA) System pressure (AB) Charge pressure (AC) Sump (AD) Activated components (AE) Load sense (AF) First pressure reduction (load sense) (AG) Trapped oil | |
Oil from sump (2) is drawn through suction screen (17) by steering pump (1). Steering pump (1) continually pumps oil when the engine is running. When there is no input to the steering system, valve envelope (22) in control spool (14) (metering pump) will be active. This will cause hydraulic cylinder (12) and (13) to be hydraulically locked. Pressure will increase in hydraulic line (26). This will cause pilot (28) to move valve envelope (18) into position. As oil pressure decreases in hydraulic line (26), the output from priority valve (3) will alternate between valve envelope (18) and (21). Almost all oil flow will be delivered through hydraulic line (25) and then on to fan motor (6) .
The outlet oil from the fan motor is delivered to control spool (9) (blade). Because the blade control pedal is in the HOLD position, oil is allowed to pass through control spool (9) and then on through hydraulic line (24). Oil in hydraulic cylinder (8) is blocked at the control spool.
Hydraulic oil in hydraulic line (24) is charge oil that is delivered to propel filter (16) .
Systems Operation for Right Turn, Blade Hold
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| Illustration 3 | g00939555 |
Hydraulic Schematic (1) Steering pump (charge) (2) Sump (3) Priority valve (6) Fan motor (7) Control valve (blade) (8) Hydraulic cylinder (blade) (9) Control spool (blade) (12) Hydraulic cylinder (steering) (13) Hydraulic cylinder (steering) (14) Control spool (metering pump) (16) Line to the propel filter (17) Suction screen (18) Valve envelope (priority valve) (19) Valve envelope (metering pump) (20) Valve envelope (blade) (21) Valve envelope (priority valve) (24) Hydraulic line (blade) (25) Hydraulic line (fan motor) (27) Hydraulic line (load sense) (28) Pilot (priority valve) (29) Valve envelope (priority valve) (AA) System pressure (AB) Charge pressure (AC) Sump (AD) Activated components (AE) Load sense (AF) First pressure reduction (load sense) (AG) Trapped oil | |
Oil from sump (2) is drawn through suction screen (17) by steering pump (1). Steering pump (1) continually pumps oil when the engine is running. Before any input to the steering system, the spool in priority valve (3) will alternate between valve envelope (18) and valve envelope (21). When an input to the steering system is applied, the pressure in load sense line (27) moves the spool in priority valve (3). The spool will alternate between valve envelope (21) and (29) depending on the severity of the input. During severe input to the steering system, the spool in the priority valve will tend to move toward envelope (29). As a result, most of the oil is delivered to the steering system. As input to the steering system is decreased, the output of the priority valve will tend to alternate between valve envelope (18) and (21). As a result, most of the oil flow will go to fan motor (6) .
During an input to the steering system for a right turn, valve envelope (19) in control spool (14) (metering pump) will be active. As a result, hydraulic cylinder (12) will extend and hydraulic cylinder (13) will retract. The oil pressure will increase at pilot (28). As a result, the priority valve will alternate between valve envelope (18) and (21). Most of the oil flow will be delivered to fan motor (6) through hydraulic line (25) .
The outlet oil from the fan motor is delivered to control spool (9) (blade). Because the blade control pedal is in the HOLD position, oil is allowed to pass through control spool (9). Oil will then go to hydraulic line (24). Oil in hydraulic cylinder (8) is blocked at the control spool.
Hydraulic oil in hydraulic line (24) is charge oil that is delivered to propel filter (16). Oil will also go through control spool (14) (metering pump) into hydraulic line (27) .