What causes a transmission to slip?

Answer 1

Hey George==If it is full of fluid, the clutched inside are brobably burned. GoodluckJoe

Currently, most automobile automatic transmissions electrically controlled, hydraulically actuated, planetary-geared transmissions.

The electrical components processes inputs, like engine speed, road speed and throttle position to select an appropriate reduction gear-set for given situation. This system then regulates circuits of pressurized fluid which act upon 'so-called' clutch packs. These clutch packs are what mechanically connect the input [engine] power through the various reductions and ultimately to the wheels. To achieve different gear reductions, some will engage, while others disengage from the gear-set. A pump, driven at the input portion of the transmission provides fluid pressure to press the clutches into position.

Slippage (the clutches not doing their job) can be caused by:

Low fluid level - The pump won't provide a large enough volume to supply everything at an appropriate pressure to fully engage clutch-packs. Slippage generates heat which reduces the viscosity of the Transmission Fluid, thereby making it less effective in it's role as a coupling-agent of the clutches, in turn allowing more slippage, eventually causing excess wear of the clutch-faces.

Contaminated fluid - Water is terrible lubricant, excessive shavings indicate wear or damage and create more, and can eventually clog filters, passages and the pump.

Excessive fluid level - Causes cavitation.

Cavitation - Disrupts the pumps ability to provide pressure, as air is compressible.

Too much input power - The clamping force of the clutch-pack is overcome, generating excessive friction.