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| Illustration 1 | g03288537 |
Views of the selector and pressure control valves. Highlighted solenoid (1) is for First Speed Forward. (1) Proportional solenoid valve for clutch pack 1 (2) Proportional solenoid valve for clutch pack 2 (3) Proportional solenoid valve for clutch pack 3 (4) Solenoid valve for clutch pack 4 (5) Solenoid valve for clutch pack 5 (6) Solenoid valve for clutch pack 6 (7) Solenoid valve for clutch pack 7 (8) Solenoid valve for clutch pack 8 (9) Selector and pressure control valve (10) Selector and pressure control valve | |
The transmission control valve provides oil flow at the correct pressure and at the proper time in order to engage the desired clutch packs. The transmission control valve is located on the left side of the transmission case.
Main Relief Valve
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| Illustration 2 | g00940967 |
(11) Spring (12) Spool (13) Passage to the oil cooler (14) Orifice (15) Passage for the oil supply (16) Slug (17) Adjustment screw for the main relief (18) Orifice | |
The main relief valve provides a restriction in the flow that sets the outlet pressure of the transmission charge pump. The oil that bypasses the main relief valve flows to passage (13) and into the oil cooler.
The main relief valve contains slug (16) that is connected to passage (15) by orifice (14) and by orifice (18) . Slug (16) creates a reaction chamber. Oil in the reaction chamber acts against the force of spring (11) in order to set the supply pressure. When the pressure of the supply oil in the reaction chamber becomes greater than the force of spring (11) , spool (12) moves to the left. Spool (12) allows partial oil flow through passage (13) to the oil cooler. When the pressure of the supply oil drops below the force of spring (11) , spool (12) moves to the right. Flow is reduced to passage (13) . When spool (12) moves to the right, oil in the reaction chamber is forced through orifice (14) . The flow through orifice (14) dampens the movement of spool (12) . The main relief valve has an external adjustment screw (17) .
Priority Reducing Valve
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| Illustration 3 | g00940968 |
(19) Spring (20) Spring (21) Spool (22) Passage from priority reducing valve (23) Passage for the oil supply (24) Orifice (25) Slug | |
The priority reducing valve reduces the supply pressure to the selector valves. The priority reducing valve reduces the supply pressure to the solenoid valves. The priority reducing valve provides priority to the selector valves and to the solenoids that control the fill for the transmission clutch. The priority reducing valve provides priority to the selector valves and to the solenoids that control the modulation for the transmission clutch.
The priority reducing valve receives oil in parallel with the main relief valve. Slug (25) provides a reaction chamber that is connected to the priority flow by orifice (24) . The oil that is contained in spool (21) acts against the force of spring (19) and against spring (20) in order to set the pressure. When the pressure of the oil (priority) in the reaction chamber becomes greater than the force of spring (19) and the force of spring (20) , spool (21) moves to the left. The flow of supply oil in passage (22) increases. When the pressure of the oil (priority) drops below the force of spring (19) and the force of spring (20) , spool (21) moves to the right. The flow of supply oil is reduced in passage (22) . When spool (21) moves to the right, oil in the reaction chamber is forced through orifice (24) . The flow through orifice (24) dampens the movement of spool (21) .
Modulation Reducing Valve
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| Illustration 4 | g00940969 |
(5) Solenoid valve for clutch pack 5 (26) Piston (27) Spring (28) Decay orifice (29) Piston (30) Spool (31) Modulation orifice (32) Spring (33) Slug (34) Spring | |
There are five modulation reducing valves. Four of the modulation reducing valves are located on selector and pressure control valve (10) . One modulation reducing valve is located on selector and pressure control valve (9) . The five modulation reducing valves provide individual pressure control for each clutch pack. The modulation reducing valves provide different pressures for the clutches (speed and range). The different pressures are obtained through different combinations of springs and orifices.
In order to pressurize number five clutch pack, solenoid (5) is energized with a 24 volt signal from the electronic control module. The electronic control module is activated by the transmission control (lever). Piston (26) moves toward the center of the valve. Piston (29) and spool (30) move away from the center of the valve. Oil from the supply passes across the modulation reducing valve in order to fill the clutch.
When the clutch is full of oil, the oil flows through orifice (31) that is contained in spool (30) . Piston (29) moves toward piston (26) . Spring (27) is compressed. The clutch pressure rises gradually.
In order to disengage the transmission clutch, the solenoid is de-energized. Piston (26) moves away from the center of the valve. The piston connects decay orifice (28) to the drain. Oil in the cavity of load piston (29) drains through decay orifice (28) . The clutch pressure drops off gradually.
Proportional Solenoid Valves
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| Illustration 5 | g01091323 |
(3) Proportional solenoid valve for clutch pack 3 (35) Spacer (36) Orifice (37) Filter (38) Passage (39) Spool (40) Spring (41) Spring (42) Slug (43) Chamber (44) Supply oil (45) Ball | |
Proportional solenoid valves connect oil from the supply to the corresponding direction clutches. There are three proportional solenoid valves that are located on selector and pressure control valve (9) .
Supply oil in passage (44) passes through filter (37) and flows through orifice (36) , and passes by ball (45) . In order to pressurize number three clutch pack, current from the electronic control module is applied to proportional solenoid (3) . The flow is restricted past ball (45) by proportional solenoid valve (3) . The restriction to the flow of oil generates pilot pressure. The pilot pressure forces spool (39) to the right. Spool (39) allows oil from the main relief valve to flow to the clutch pack. The clutch pack will fill with oil. When the clutch pack is full of oil, the pressure gradually begins to increase. Oil from the clutch pack will flow through passage (38) in spool (39) and flow into chamber (43) . The oil acts on spool (39) in order to generate a force. The force that is generated plus the force from spring (40) opposes the force on spool (39) that is generated by the pilot pressure. The two forces act on the spool in order to achieve a balance of forces. The balance maintains a clutch pressure that is proportional to the current that is applied to the proportional solenoid valve.
Clutch Pedal
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| Illustration 6 | g00921607 |
View from inside of the operator compartment (46) Clutch pedal | |
Clutch pedal (46) will vary the power that is transmitted to the drive wheels. In order to control the power to the drive wheels, the directional clutch pressure is varied by altering the current to the proportional solenoid valves.
When pedal (46) is gradually depressed, the electronic control module reads the position sensor for pedal (46) . The electronic control module adjusts the current that is applied to the proportional solenoid valve. The proportional solenoid valve reduces the direction clutch pressure.
Note: When pedal (46) is depressed, the direction clutch pressure is reduced to tank pressure.
When pedal (46) is slowly released, the electronic control module reads the position sensor for pedal (46) . The electronic control module then adjusts the current that is applied to the proportional solenoid valve. The proportional solenoid valve increases the direction clutch pressure.
Note: When pedal (46) is released, the direction clutch pressure is automatically modulated by the electronic control module.
Passages for the Transmission Control Valve
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| Illustration 7 | g00903842 |
View of the Back of the Transmission Control Valve (1) Passage for clutch 1 (2) Passage for clutch 2 (3) Passage for clutch 3 (4) Passage for clutch 4 (5) Passage for clutch 5 (6) Passage for clutch 6 (7) Passage for clutch 7 (8) Passage for clutch 8 (9) Passage for lubrication oil (10) Passage for the elevated drain (11) Passage for supply oil (12) Passage to the cooler (13) Passage for lubrication (14) Passage for the elevated drain (15) Passage for the drain | |
Passages for the Transmission Case
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| Illustration 8 | g00903817 |
View of the Left Side of the Transmission Case (1) Passage for clutch 1 (2) Passage for clutch 2 (3) Passage for clutch 3 (4) Passage for clutch 4 (5) Passage for clutch 5 (6) Passage for clutch 6 (7) Passage for clutch 7 (8) Passage for clutch 8 (9) Passage from the transmission oil filter (10) Port for the temperature sensor (11) Passage to the oil cooler (12) Passage from the oil cooler (13) Passage for the elevated drain from the clutch packs (14) Passage for the oil supply to the control valve (15) Passage for the lubrication oil for the input shaft (16) Passage for the lubrication oil for clutch (forward) (17) Passage for the lubrication oil for the transmission clutch (reverse and second) (18) Passage for lubrication oil to the transmission clutch shaft (19) Passage for the lubrication oil (20) Passage for the lubrication oil for the transmission clutch shaft (21) Drain passage from control valve (22) Relief valve port for the lubrication oil (23) Passage to the relief valve for the lubrication oil (24) Oil cooler bypass (25) Passage to the port for the oil cooler and passage to the bypass for the oil cooler | |