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Belt pulley, function - GF83.55-P-2103-02P

Function under normal operating conditions 

Under normal operating conditions the rubber (2) is deformation resistant. Thus it transmits the belt pulley's (3) torque to the hub (1) and at the same time to the refrigerant compressor shaft, whereby the hub (1) and belt pulley (3) turn in the direction of the arrow.

The refrigerant compressor torque < the rubber torque limit (2). In this operating condition, the rubber (2) acts as a shock absorber by inhibiting resonance via the belt with other engine components.

Fig 1: Belt Pulley Function Diagram Under Normal Operating Conditions
G07110097Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Function of refrigerant compressor lock up 

When the refrigerant compressor locks up, the torque required to drive the refrigerant compressor must be greater than the torque present on the belt pulley (3). This causes slip to occur between the belt pulley (3) and hub (1) because of the deformation and wear of the rubber (2). Thus the belt pulley (3) continues to rotate even with a locked up refrigerant compressor.

The refrigerant compressor torque > the rubber torque limit (2).

In this operating condition, the rubber (2) acts as a belt pulley protection device.

Fig 2: Belt Pulley Function Diagram Upon Refrigerant Compressor Lock Up
G07110098Courtesy of MERCEDES-BENZ OF NORTH AMERICA.