Mercedes-Benz G-class W463 - Repair manual and operation

9.1. The four-wheel drive - the general information

Basic principles of the organization of the constant four-wheel drive

General information

The torque developed by the engine is transmitted through AT to the transfer case equipped with interaxal differential and from there, by means of driveshafts, to differentials of assemblies of forward and back bridges.

On all models considered in the present manual the four-wheel drive is executed not disconnected. The mechanism of blocking of interaxal differential is provided in a design of the two-level transfer case. The reducer of the transfer case is completely synchronized thanks to what switching of steps can is made during the movement. Also mechanisms of compulsory blocking of both interwheel differentials are provided.

Order of blocking of differentials

Management of blocking of differentials is made by means of the switches which are built in in the central part of the dashboard of the car (see the Section Governing bodies and the equipment of salon). Blocking has to be made strictly in a certain sequence: INTERAXAL DIFFERENTIAL —› ZADNY Bridge —› PEREDNY Bridge. Blocking of differentials should be included only in difficult terrains, at drives through water or on the roads covered with snow, ice or dirt.

In difference from cars with the connected four-wheel drive here the torque is transferred to both axes constantly. Redistribution of power between axes provides interaxal differential. The mode of rigid communication between axes, necessary for achievement of the maximum traction effort, is provided with blocking of this differential.

To advantages of the constant four-wheel drive stability of characteristics of controllability of the car, a possibility of use of the lower number of the transfer case treat without blocking and consequently, on any roads without restriction on coupling. Besides such car always is in a condition of "the increased combat readiness". Compulsory blocking of differentials can be used as an additional tool of increase in passability in case of problems on off road terrain. It should be noted that the maximum draft at bad coupling with soil can be received only by means of compulsory blocking as any automatic equipment assumes the pro-slipping of wheels (if there is no pro-slipping, then blocking does not work) by all means leading to losses of traction effort

The constant four-wheel drive and shortcomings is not deprived. Such car should turn all driveshafts and half shafts. As a result on asphalt its transmission it is also noisy, as well as the connected four-wheel drive with the switched-on wheel couplings, and also provides a "all-wheel drive" increase to fuel consumption.

Nevertheless the constant four-wheel drive provides nevertheless more positive moments, than negative, especially for the real SUVs.

Elements of management of blocking of differentials

and — the Tank with — Pressure head blocks of switching of blocking of interwheel differentials of assemblies of forward and back bridges	d — Executive cylinders of switching of blocking of interwheel differentials of assemblies of forward and back bridges

Function chart of a hydraulic actuator of blocking of differentials

1 — the Tank 2 — Pressure head blocks of switching of blocking of interwheel differentials of assemblies of forward and back bridges 3 — Executive cylinders of switching of blocking of interwheel differentials of forward (VA) and back (HA) of bridges	4 — the Arch of the right wheel and — the Contour of supply of hydraulic liquid b — Working contours of executive cylinders

Design of the hydropneumatic pressure head block

1 — air Access 2 — To the tank of hydraulic liquid	3 — To the executive cylinder of the mechanism of management of blocking 4 — the Soaking-up union (depression)

Scheme of an arrangement of mechanical components of management of blocking of interwheel differentials

and — Sapun of ventilation of a case of the bridge	b — the Switching finger

Scheme of an arrangement of mechanical components of management of blocking of interaxal differential

1 — a switching Fork 2 — the Executive cylinder	3 — the Operating switch (S76/2)

Scheme of an arrangement of pneumatic components of management of blocking of differentials

M14/1 — the Auxiliary vacuum pump (petrol models) 67 — the Vacuum pump (diesel models) and — the Vacuum receiver (0.4 l)	b — Pressure head blocks of switching of blocking of interwheel differentials of assemblies of forward and back bridges

The function chart of a pneumatic actuator of blocking of differentials on DIESEL models (blocking of interaxal differential and interwheel differential of the back bridge are included

and — the Element is activated b — switching Pressure with — giving Pressure d — Hydraulic pressure 1 — the Transfer case (interaxal differential) 2 — the Electromagnetic valve (Y68) of switching of blocking of interaxal differential 3 — the Replaceable filter of the electromagnetic valve 4 — To the vacuum pump 5 — the Control valve 6 — the Electromagnetic valve (Y68/1) of switching of blocking of interwheel differential of the back bridge 7 — the Electromagnetic valve (Y68/2) of switching of blocking of interwheel differential of the forward bridge 8 — the Vacuum receiver of the brake system in a cross beam of a frame: 4.4 l (auxiliary vacuum receiver: 1.8 k)

9 — To the servo-driver of the vacuum amplifier of brakes 10 — the Vacuum receiver of blocking of differential (0.4 l) 11 — the Pressure head block of switching of blocking of interwheel differential of the forward bridge 12 — the Union of a hydraulic path of management of blocking of interaxal differential of the forward bridge 13 — To the tank of hydraulic liquid 14 — the Union of a hydraulic path of management of blocking of interaxal differential of the back bridge 15 — the Pressure head block of switching of blocking of interwheel differential of the back bridge 16 — the Arch of the right wheel

The function chart of a pneumatic actuator of blocking of differentials on PETROL models (blocking of interaxal differential and interwheel differential of the back bridge are included

and — the Element is activated b — switching Pressure with — giving Pressure d — Hydraulic pressure 1 — the Transfer case (interaxal differential) 2 — the Electromagnetic valve (Y68) of switching of blocking of interaxal differential 3 — the Replaceable filter of the electromagnetic valve 4 — To the inlet pipeline 5 — the Control valve 6 — the Electromagnetic valve (Y68/1) of switching of blocking of interwheel differential of the back bridge 7 — the Electromagnetic valve (Y68/2) of switching of blocking of interwheel differential of the forward bridge 8 — the Vacuum receiver of the brake system in a cross beam of a frame: 4.4 l (auxiliary vacuum receiver: 1.8 k)

9 — To the servo-driver of the vacuum amplifier of brakes 10 — the Vacuum receiver of blocking of differential (0.4 l) 11 — the Pressure head block of switching of blocking of interwheel differential of the forward bridge 12 — the Union of a hydraulic path of management of blocking of interaxal differential of the forward bridge 13 — To the tank of hydraulic liquid 14 — — the Union of a hydraulic path of management of blocking of interaxal differential of the back bridge 15 — the Pressure head block of switching of blocking of interwheel differential of the back bridge 16 — the Arch of the right wheel 17 — the Auxiliary electric vacuum pump (M14/1)

The scheme of an arrangement of electric components of management of blocking of differentials (1 of 2)

1 — the Switch of blocking of interaxal differential 1.1 — Control lamp of inclusion of blocking (yellow) 1.2 — Control lamp of functioning of blocking (red) 2 — the Switch of blocking of interwheel differential of the back bridge 2.1 — Control lamp of inclusion of blocking (yellow) 2.2 — Control lamp of functioning of blocking (red) 3 — the Switch of blocking of interwheel differential of the forward bridge 3.1 — Control lamp of inclusion of blocking (yellow)

3.2 — Control lamp of functioning of blocking (red) N30/2 — the Module of management of blocking of differentials S76/2 — the Operating sensor switch of blocking of interaxal differential S76/3 — the Operating sensor switch of blocking of interwheel differential of the back bridge S76/4 — the Operating sensor switch of blocking of interwheel differential of the forward bridge

The scheme of an arrangement of electric components of management of blocking of differentials (2 of 2)

3 — the Relay (K36) of activation of the auxiliary electric vacuum pump (M14/1) on petrol models 29, 30 — Safety locks K1/1 = K1/2 (diesel models) K1/2 — Protection against electric overloads (petrol models) Y68 — the Electromagnetic valve of switching of blocking of interaxal differential	Y68/1 — the Electromagnetic valve of switching of blocking of interwheel differential of the back bridge Y68/2 — the Electromagnetic valve of switching of blocking of interwheel differential of the forward bridge