ENGINE OPERATION - Operating Instructions 1 Slow Down Around Curves Braking Truck on Grade CAUTION Never exceed governed engine speed because engine damage can occur. Operating engine beyond the gov- erned speed causes additional strain on valve train and internal engine com- ponents. Operate the engine within governed engine speed. 25 MPH NOTE Once you have determined what the safe speed is for your vehicle, operate the engine brakes with the transmis- sion in the lowest gear that will not cause the engine speed to exceed the rated engine speed. The optimum braking power of the engine brakes is reached at rated engine speed. Cor- rect gear selection, therefore, is criti- cal.
The engine brake is NOT intended as the primary brake for the vehicle, nor is it an emergency brake. The engine brake only helps the service brakes by using pressure to slow the drivetrain. Use the service brakes for quick stops. WARNING DO NOT drive with frequent or contin- uous use of the service brakes. This can overheat the brakes and result in excessive lining wear, increased stop- ping distances, possibly an accident and may lead to personal injury. Be- fore descending a steep grade, shift to a lower gear, keep the vehicle speed low, and avoid continuous application to the brakes. Failure to comply may result in death, personal injury, equip- ment or property damage.
The selector switch can be used to vary braking power as road conditions change. Vehicle service brakes must be used when additional braking power is required. 30 Y53-1183-1E1 (04/16/18)