Subaru Legacy/Outback

1999-2003 of release

Repair and operation of the car

chargers bar

Interaxal differential - the device and the principle of functioning

Design of interaxal differential with the viscous coupling


1 — the Conducted gear wheel of the distributing mechanism 2 — the Leading gear wheel of the distributing mechanism 3 — the Viscous coupling	4 — Interaxal differential with the viscous coupling 5 — the Shaft of the leading gear wheel of the main transfer 6 — the Conducted (secondary) shaft

Design of the viscous coupling of interaxal differential


1 — the Ring of X-figurative section 2 — the Sealing ring 3 — the Remote ring 4 — the Disk of external gearing	5 — the Disk of internal gearing 6 — the Ring of X-figurative section 7 — the Back lateral gear wheel

The description of procedures of removal, service and installation of interaxal differential is provided in the Section Removal, service and installation of interaxal differential.

Design

The interaxal differential is executed according to the planetary symmetric scheme on conic gear wheels. Design feature used on the models of interaxal differential considered in the present manual is use of the viscous coupling.

The interaxal differential carries out two functions: distribution of a torque of the engine between power shafts of lobbies and back wheels and repayment of distinction in speeds of rotation of lobbies and back wheels.

The torque of the engine is transferred to interaxal differential from the conducted (secondary) shaft of transmission, being distributed then between shaft of the leading gear wheel of the main transfer (directly through conic gear wheels) and cardan in bulk (through the leader and conducted gear wheels of the distributing mechanism).

At normal coupling of lobbies and back wheels with the paving provided with adequate distribution of torques working function of conic gear wheels of differential it is limited to the viscous coupling.

Some disks (plates) of external and internal gearing located serially are installed in the case of the viscous coupling. In hermetically closed cavity formed by the case and a back lateral gear wheel of differential air and silicone oil mix is filled in.

The part of disks of the coupling is equipped with the external vents entering gearing with the case of interaxal differential. On vents of disks of internal gearing the lateral gear wheel is put.

For distributing of disks of external gearing between them special remote rings are established. Between disks of internal gearing such rings are not provided that provides certain freedom of their movement in the axial direction.

Two sealants executed in the form of rings of H-shaped section, prevent an effluence from the coupling of silicone oil in case of increase of its pressure at a big difference in speeds of rotation of lobbies and back wheels.

Principle of functioning

Losses of silicone oil of the viscous coupling are fraught with an assembly exit out of operation! Pressure in the coupling can increase considerably when speeds of rotation of lobbies and back wheels considerably differ from each other for a long time, for example, during towage of the vehicle with a separation of one of axes from the earth.

Distribution of a torque of the engine at the normal movement of the car


1 — an engine Torque A — To forward differential	B — To back differential

In the absence of a difference of speeds of rotation of lobbies and back wheels the interaxal differential transfers an engine torque on lobbies and back wheels concerning 50:50, and at emergence of such difference, makes its controlled clearing it by means of the viscous coupling.

At the rectilinear movement of the vehicle with a constant speed on the equal road all wheels rotate with an identical speed and the interaxal differential evenly distributes an engine torque between forward and back axes. As disks of external and internal gearing to the viscous coupling remain motionless from each other, the shift moment between them does not arise. During commission of turns at low speeds of the movement the difference in speeds of rotation arises not only between right and left, but also and between lobbies and back wheels, - forward wheels rotate quicker than the back. A problem of interaxal differential is repayments of this difference for the purpose of ensuring smoothness of the movement and extension of service life of tires. Despite insignificance of a difference of speeds of rotation of wheels in these conditions, operation of the viscous coupling leads to redistribution of a torque of the engine in favor of a back axis.

At the movement on rough and slippery roads in a case when forward wheels start revolving, the general difference between speeds of rotation of lobbies and back power shafts leads to emergence in the viscous coupling considerably of the shift moment. As a result, the torque transferred to back wheels becomes much more, than transferred to the scrolled forward wheels.

At sharp dispersal from a place when back wheels are on a slippery surface, occur the shift of the center of gravity of the car leading to pro-slipping of back wheels. In this situation the moment of shift arising in the viscous coupling leads to redistribution of a torque of the engine in favor of forward wheels.