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
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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
Function chart of a hydraulic actuator of blocking of differentials
Design of the hydropneumatic pressure head block
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1 — air Access |
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
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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
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1 — a switching Fork |
3 — the Operating switch (S76/2) |
Scheme of an arrangement of pneumatic components of management of blocking of differentials
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
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
The scheme of an arrangement of electric components of management of blocking of differentials (1 of 2)
The scheme of an arrangement of electric components of management of blocking of differentials (2 of 2)