The LoadLeash for Cummins 6.7L by Pacbrake is an engine brake which works in tandem with the vehicle’s variable geometry turbo (VGT) exhaust brake. It functions by holding the exhaust valves slightly off the seat during the complete engine cycle, with the VGT providing exhaust backpressure and increased boost pressure.
Two braking cycles are achieved.
1. The first braking cycle is accomplished during the exhaust stroke when the piston is pushing the cylinder pressure past the open exhaust valve against the “closed” VGT.
2. The second braking cycle occurs during the compression stroke when the piston is pushing the cylinder pressure past the open exhaust valve against the “closed” VGT.
♦ The expansion stroke is eliminated by the open exhaust valve.
With work being done on both the compression stroke and the exhaust stroke, we are now doing retarding work on two engine cycles.
For optimal braking, the following switches must be in the ‘ON’ position:
♦ Tow/Haul (to provide auto-downshifting in RAM/Sterling trucks with automatic transmissions)
♦ LoadLeash Switch
♦ Exhaust Brake Switch
An alternative method is manually downshifting using the +/- switch on the column selector. This can be achieved with the Tow/Haul ‘OFF’ and the LoadLeash & Exhaust Brake switches ‘ON’.
Pacbrake’s LoadLeash, used in tandem with the VGT exhaust braking feature, will result in a 50% increase in retarding HP when measured at the rear wheels.
The LoadLeash engine brake provides over 300 RHP. In addition to enhanced control and reduced brake fade, Pacbrake’s LoadLeash can extend service brake life by up to 5 times!
“Seat of the pants” feel is noticeable, particularly above 2500 RPM with a heavy load. Manual downshifting may be required. The LoadLeash is stronger at all RPMs and in most cases will control the vehicle/load in a chosen gear without the rapid downshifting and high engine RPM experienced with the exhaust brake use alone.