Transmission-independent power take-off (NMV) shift module, component description

Location

W26.45-1468-81

 The live power take-off is available in two variants:
Clutch-dependent variant A (code N4Y (Live power take-off, clutch-dependent, MB, 1.2) or code N4Z (Live power take-off, clutch-dependent, MB, 1.65)). Variant A is only suitable for use when the vehicle is stationary.
Clutch-part dependent variant B (code N4W (Live power take-off, clutch-part dependent, MB, 1.2) or code N4X (Live power take-off, clutch-part dependent, MB, 1.65)). Variant B is suitable for use when the vehicle is stationary and when it is being driven.

The live power take-off shift module (Y502) is on the left side of the transmission housing relative to the direction of travel.

Task

The live power take-off shift module (Y502) mechanically actuates the shift mechanism for adjusting the sliding sleeve and also detects the shift position.

Body

W26.45-1472-12

Function

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Neutral shift position (I), (variant A and variant B)

In the neutral shift position, the live power take-off is not driven. The "extend" live power take-off solenoid valve (Y502 y1) and the "retract" live power take-off solenoid valve (Y502 y2) are deenergized. The compressed air lines to the shift cylinder (1) are unpressurized. The piston rod (2) and gearshift arm (4) are in their respective center position. The sliding sleeve (5) is not connected to the transmission input shaft or the hollow shaft.

Live power take-off engaged shift position (II), (variant A)

To engage the live power take-off, the "extend" live power take-off solenoid valve (Y502 y1) is energized by the transmission control unit (TCM) (A5). Reservoir pressure (A) is applied to the upper working chamber of the shift cylinder (1) and the piston rod (2) is extended. The sliding sleeve (5) is pushed via the shift hub (3) and the gearshift arm (4) onto the external toothing of the transmission input shaft and into the live power take-off engaged shift position (II).

During this process, the live power take-off position sensor (Y502 b1) permanently detects the adjustment range and the position of the piston rod (2) and sends a corresponding signal to the transmission control unit (TCM) (A5). The live power take-off is connected to the transmission input shaft dependent on the clutch.

Live power take-off engaged shift position (III), (variant B)

To engage the live power take-off, the "extend" live power take-off solenoid valve (Y502 y1) is first energized by the transmission control unit (TCM) (A5). Reservoir pressure (A) is applied to the upper working chamber of the shift cylinder (1) and the piston rod (2) is extended. The sliding sleeve (5) is pushed via the shift hub (3) and the gearshift arm (4) onto the external toothing of the transmission input shaft and into the intermediate position (II).

During this process, the live power take-off position sensor (Y502 b1) permanently detects the adjustment range and the position of the piston rod (2) and sends a corresponding signal to the transmission control unit (TCM) (A5). The live power take-off is connected to the transmission input shaft dependent on the clutch.

The "retract" live power take-off solenoid valve (Y502 y2) is then energized by the transmission control unit (TCM) (A5). Reservoir pressure (A) is applied to the lower working chamber of the shift cylinder (1) and the piston rod (2) is retracted. The sliding sleeve (5) is pushed by means of the shift hub (3) and the gearshift arm (4) via the neutral shift position (I) onto the internal toothing of the hollow shaft and into the live power take-off engaged shift position (III).

During this process, the live power take-off position sensor (Y502 b1) permanently detects the adjustment range and the position of the piston rod (2) and sends a corresponding signal to the transmission control unit (TCM) (A5). The live power take-off is connected directly to the engine by means of the hollow shaft via the clutch pressure plate.

Disengage power take-off (variant A and variant B)

To disengage the live power take-off, the "extend" live power take-off solenoid valve (Y502 y1) and the "retract" live power take-off solenoid valve (Y502 y2) are energized by the transmission control unit (TCM) (A5). These solenoid valves switch to the flow-through position, and reservoir pressure (A) is applied to both working chambers of the shift cylinder (1). The piston rod (2) is automatically moved to the neutral position. The sliding sleeve (5) is pushed via the shift hub (3) and the gearshift arm (4) into the neutral shift position (I) and is thus connected neither to the transmission input shaft (variant A) nor to the hollow shaft (variant B).

During this process, the live power take-off position sensor (Y502 b1) permanently detects the adjustment range and the position of the piston rod (2) and sends a corresponding signal to the transmission control unit (TCM) (A5).

Disengage or engage live power take-off manually

W26.45-1474-76

The live power take-off can be disengaged manually:

 Detach the cover (6) from the shift hub (3).

 Shift the live power take-off to a load-free position via the shift hub (3) using a suitable tool (7).

 Attach the cover (6) to the shift hub (3).

The live power take-off can be engaged manually:

 Turn the ignition key to the OFF position.

 Detach the cover (6) from the shift hub (3).

 Shift the piston rod to the lower position using a suitable tool (7).

 Attach the cover (6) to the shift hub (3).

 Start the engine and operate the power take-off 3 switch (S73) at the same time.