Exhaust brake usage can cause high temperatures in the automatic
transmission due to torque converter slippage if a lockup device is not used.
Only 10% to 80% of the retarding force is transferred through the fluid
coupling of most torque converters. The BD TorqLoc commands the lock-up
clutch of the torque converter to stay engaged when the BD Exhaust Brake is
activated. This allows up to 100% of the retarding force to be transferred
while in 3rd and 4th gear. Also, transmission oil temperatures will remain
low because of little or no slippage occurring in the converter in these
gears.

Maintains lock-up when the exhaust brake is activated
Ensuring 100% of the retarding force is being transferred in 3rd and 4th
gears
Prevents slippage and subsequent high oil temperatures
TorqLoc with its three position switch allows for manual command of the
lock-up as well as AutoLoc and stock operations