450F Backhoe Loader Transmission (Autoshift) Caterpillar


Transmission Control

Usage:

450F HJR



Illustration 1g03229316

(1) Solenoid for clutch 2

(2) Solenoid for clutch 3

(3) Reverse solenoid

(4) Forward low solenoid

(5) Forward high solenoid




Illustration 2g03229336

(6) All wheel drive solenoid

(7) Solenoid for clutch 1

The solenoid control valves for the transmission are installed on the top and on the right side of the transmission housing. The solenoid control valves for the transmission control the FORWARD, REVERSE, FIRST, SECOND, THIRD, and NEUTRAL functions of the transmission.

The solenoid control valves direct the pressurized oil to either the forward clutch packs or to the reverse clutch packs. In the NEUTRAL position, clutch pressure is sent through the torque converter and the clutch pressure is sent through the transmission oil cooler. The transmission oil is dumped back to the transmission case. The reverse solenoid of the solenoid control valve for the transmission is electrically connected with the backup alarm switch. The backup alarm switch activates the backup alarm.




Illustration 3g03230239

(A) Neutralizer switch

(B) Direction control lever

(C) All wheel drive switch




Illustration 4g03231836

(D) Neutralizer button (If equipped)

The neutralizer switch is located on either the left side of the dash or the loader control lever. The neutral lock switch on the left side of the dash disables all transmission solenoids. The neutralizer switch that is located on the loader control lever disengages the solenoids for direction control.

If the machine is turned off, and the direction control lever is left in the FORWARD position or the REVERSE position, the machine will not be able to start until the direction control lever is returned to the NEUTRAL position.

The neutralizer switch that is located on the loader control lever also is a downshift control when the autoshift function is selected. If the neutralizer switch is pressed and released within 0.5 seconds, the transmission will downshift to the next lower speed. The transmission can be downshifted multiple speeds if the button is pressed quickly multiple times.

Note: The transmission will downshift only if an engine overspeed will not occur.




Illustration 5g03230239

(A) Neutralizer switch

(B) Direction control lever

(C) All wheel drive switch

The solenoids that are located in the solenoid control valves are actuated by electricity. The solenoids are actuated by the direction control lever that is on the steering wheel column.

When the solenoid control valve is de-energized, the springs center the spool, which blocks the oil flow from the transmission pump. The oil pressure in the direction clutch decreases and the direction clutch disengages when oil flow to the transmission is blocked. When the transmission solenoid is energized, the oil passages to the transmission are opened. The energized solenoid permits the filling of the direction clutches. The energized solenoids also allow the pressure to build up in the transmission.

All Wheel Drive




Illustration 6g01433155

All wheel drive in NEUTRAL

(1) Oil pump

(2) Pump pressure tap

(3) Oil filter with bypass

(4) Autoshift electronic control module

(5) All wheel drive clutch

(6) Clutch 2

(7) Clutch 3

(8) Reverse clutch

(9) Forward high clutch

(10) Forward low clutch

(11) Clutch 1

(12) Pressure regulator

(13) Torque converter inlet relief valve

(14) Torque converter

(15) Temperature sensor for the torque converter outlet

(16) Oil cooler

(17) Test port for the lubrication pressure

(18) Transmission lubrication system

(19) Suction screen

The all wheel drive attachment will improve mobility and overall performance of the loader in conditions of poor traction.

The front drive axle may be engaged at any time by activating the all wheel drive switch on the left side of the front console. This switch may be activated when the vehicle is stopped or while the vehicle is moving. The front drive axle may also be engaged by placing the all wheel drive switch in the position for all wheel drive braking and depressing the brake pedal.




Illustration 7g03230239

(A) Neutralizer switch

(B) Direction control lever

(C) All wheel drive switch

The following components are required with the all wheel drive attachment: all wheel drive switch, all wheel drive solenoid valve, transmission for the all wheel drive, clutch pack for the all wheel drive that is on the output shaft for the all wheel drive, a steerable front drive axle and front drive shaft with a guard. The front drive shaft connects the output shaft for the all wheel drive with the steerable front drive axle.

When the engine is running, oil pump (1) pulls oil from the reservoir through suction screen (19) to the pump. The oil pump sends the oil through filter (3) and to the control solenoid valve for the transmission.

With the direction control lever in the NEUTRAL position, oil flow is blocked by the solenoid control valve.

This action allows oil that is not needed by the transmission circuit to flow through the pressure regulator to the torque converter.

Oil flows to the solenoid valve for all wheel drive (5). With the all wheel drive switch in the OFF position, the oil is blocked by the all wheel drive solenoid valve.

With the all wheel drive switch in the ON position, a passage will open in the solenoid valve and clutch pack (5) will become pressurized.

With the all wheel drive switch in the ALL WHEEL DRIVE BRAKING position, oil is then blocked by the solenoid valve until both brake pedals are engaged. When both brake pedals are engaged, a passage will open in the solenoid valve and clutch pack (5) will become pressurized.

Run The Engine (Forward First Speed Gear)




Illustration 8g01433158

(1) Oil pump

(2) Pump pressure tap

(3) Oil filter with bypass

(4) Autoshift electronic control module

(5) All wheel drive clutch

(6) Clutch 2

(7) Clutch 3

(8) Reverse clutch

(9) Forward high clutch

(10) Forward low clutch

(11) Clutch 1

(12) Pressure regulator

(13) Torque converter inlet relief valve

(14) Torque converter

(15) Temperature sensor for the torque converter outlet

(16) Oil cooler

(17) Test port for the lubrication pressure

(18) Suction screen

When the engine is running, oil pump (1) pulls oil from the reservoir through suction screen (19) to the pump. The oil pump sends the oil through filter (3) and to the control solenoid valve for the transmission.

When the direction control lever on the steering wheel column is moved to the FORWARD position, the forward low solenoid is electrically activated. The electrical activation of the forward solenoid overrides the centering spring. The spool will then move. Pressurized oil will be able to flow to the forward low direction clutch (10) .

A Pressure regulator within the control solenoid valve establishes a constant flow and pressure of oil to the direction clutches. This action allows oil that is not needed by the transmission circuit to flow to the torque converter.

The FORWARD position and the first speed gear direct oil to forward low clutch pack (10) and clutch pack (11) for clutch 1.

When the clutch pack obtains system operating pressure, the pressure regulator valve opens. The pressure regulator valve helps maintain system operating pressure to the clutch packs.

Torque converter inlet relief valve (13) controls maximum pressure to the torque converter in order to prevent damage during cold starts. Torque converter pressure is maintained in the torque converter by the restrictions that are created by the oil cooler and the oil lines that are leaving the torque converter.

When the switch for the all wheel drive is in the ON position, oil will flow through a small passage to the solenoid valve for the all wheel drive. When the all wheel drive solenoid is energized, a passage opens to a tube. The tube provides an oil passage that leads to the clutch pack for all wheel drive (5) .

Run The Engine (Reverse First Speed Gear)




Illustration 9g01433163

(1) Oil pump

(2) Pump pressure tap

(3) Oil filter with bypass

(4) Autoshift electronic control module

(5) All wheel drive clutch

(6) Clutch 2

(7) Clutch 3

(8) Reverse clutch

(9) Forward high clutch

(10) Forward low clutch

(11) Clutch 1

(12) Pressure regulator

(13) Torque converter inlet relief valve

(14) Torque converter

(15) Temperature sensor for the torque converter outlet

(16) Oil cooler

(17) Test port for the lubrication pressure

(18) Suction screen

When the engine is running, oil pump (1) pulls oil from the reservoir through suction screen (18) to the pump. The oil pump sends the oil through filter (3) and to the control solenoid valve for the transmission.

When the direction control lever on the steering wheel column is moved to the REVERSE position, the reverse solenoid is electrically activated. The electrical activation of the reverse solenoid overrides the centering spring. The spool will then move. Pressurized oil will be able to flow to the reverse direction clutch (8) .

The REVERSE position and the first speed gear direct oil to reverse clutch pack (8) and to clutch pack (11) for clutch 1.

When the clutch pack obtains system operating pressure, the pressure regulator valve opens. The pressure regulator valve helps maintain system operating pressure to the clutch packs.

Torque converter inlet relief valve (13) controls maximum pressure to the torque converter in order to prevent damage during cold starts. Torque converter pressure is maintained in the torque converter by the restrictions that are created by the oil cooler and the oil lines that are leaving the torque converter.

When the switch for the all wheel drive is in the ON position, oil will flow through a small passage to the solenoid valve for the all wheel drive. When the all wheel drive solenoid is energized, a passage opens to a tube. The tube provides an oil passage that leads to the clutch pack for all wheel drive (5) .

Caterpillar Information System:

450F Backhoe Loader Transmission (Autoshift) Transmission
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