In normal operation for locomotive/carriage trains, on descending and level running, the train is normally braked (service braking) using the locomotive. This uses compression braking – the energy is absorbed by using the cylinders as pumps, then dumping the pressure, similar to a Jake brake – on steam locomotives, hydraulic braking on the diesel locomotives. The diesel-electric railcars were service braked using hydraulic brakes and dynamic braking, during which power was dissipated in roof-mounted resistors, creating a distinct heat shimmer when the vehicles were descending and shortly afterwards. The hand brakes are used to bring a train to a complete stand from low speed, and as a parking brake.