OM2021 12/01 Safety - Section 2 General Safety Page 2-25 A Speed/Grade decal showing Retarding Capacities is applied to the lower left-hand corner of the cab windshield. This decal is designed to help the oper- ator maintain a safe vehicle speed while descending a grade with a loaded truck. The operator should pre-select a ground speed and gear range for a known grade that will permit contin- uous retarder operation within the LIMITS OF THE CHART. For efficient retarder operation, the operator should: Maintain engine RPM between 1800 - 2400 RPM MAXIMUM, and Observe the Brake Oil Temperature gauge to make certain the Brake Oil Temperature does not exceed 248°F (120°C).
If the Brake Oil Temperature exceeds this limit, move the transmission range selector lever to a lower gear and use the foot-operated service brakes to reduce the truck ground speed. This will allow the transmission to shift to the next lower gear range for more efficient cooling. If the Brake Oil Temperature continues to exceed 248°F (120°C), select a safe area out of the way of other traffic, stop the truck, move the transmission range selector lever to the Neutral (N) position, and operate the engine at approximately 1200 RPM until the Brake Oil Temperature gauge registers in the "green" range.
A plate attached to the left rear of the optional FOPS structure, over the cab states the Rollover Protective Struc- ture and Falling Object Protective Structure meets various SAE performance requirements. Do not make modifications to the FOPS structure or attempt to repair damage without written approval of the manufacturer. Unauthorized repairs will void certification.