Sunday, December 16, 2012

777F Off-Highway Truck : Transmission Control

Transmission control
(1) Transmission control lever
(2) Hoist control lever
(3) Lock for the transmission control lever
(4) Transmission upshift switch(5) Transmission downshift switch

Transmission control lever
(1) Transmission control lever(6) Position sensor for the transmission shift lever

Transmission control lever (1) and hoist control lever (2) are located on a console. The console is located to the right of the seat for the operator.

The transmission has seven forward speeds and one reverse speed.

Lock (3) must be pressed before the transmission control lever (1) can be moved from "P" PARK position, "R" REVERSE position, "N" NEUTRAL position and from "D" DRIVE position to "N" NEUTRAL position.

The parking brakes are engaged when transmission control lever (1) is in the "P" Park position.

Placement of transmission control lever (1) in the "1" First gear position or "2" Second gear position will engage only the indicated gear. Placing the transmission control lever in the "1" First gear position or "2" Second gear position will not allow an automatic upshift or an automatic downshift of the transmission. This feature will allow the operator to hold the transmission in the lower gears when operating in poor under foot conditions.

Placement of transmission shift lever (1) in the "D" Drive position will enable automatic upshift and downshift of the transmission. The top gear is selected by the use of upshift switch (4) and downshift switch (5) in the transmission shift lever. Pressing the top gear upshift switch will shift the maximum top gear selected to the next higher gear through seventh gear. Pressing the top gear downshift button will lower the maximum top gear selection to the next lower gear through first gear. The selected top gear and the actual gear will be displayed on the transmission gear display.

Position sensor (6) provides the Chassis Electronic Control Module (ECM) with information about the position of transmission shift lever (1) . The shift lever switch is mechanically connected to the position sensor inside the shift console.

Position sensor (6) is a Pulse Width Modulated (PWM) sensor. The position sensor sends a (PWM) signal to the Chassis (ECM). The Chassis (ECM) determines the desired transmission gear and energizes the solenoids for the transmission clutch modulation valves in order to shift the transmission speed-up or down.

MARYGAR