What does hydraulic retarder mean for trucks?
3 Answers
Hydraulic retarder, also known as hydraulic deceleration device, is a type of vehicle retarder that reduces the speed of a vehicle through hydraulic means. Here is some extended information: 1. Usage scenario: When a truck is going down a long slope, although the exhaust brake can achieve good braking effect, it has limited effectiveness for heavy-duty mining dump trucks and can cause some degree of damage to the engine. Therefore, mining dump trucks equipped with hydraulic mechanical transmissions are also equipped with hydraulic retarders. 2. Hydraulic retarder: The stator of the hydraulic retarder is also the retarder housing, connected to the rear of the transmission or the vehicle frame. The rotor is connected to the drive shaft through a hollow shaft, and both the rotor and stator are cast with blades. During operation, by operating the control valve, pressure is applied to the oil reservoir, allowing the working fluid to fill the working chamber between the rotor and stator. When the rotor rotates, it exerts a torque on the stator through the working fluid, and the reverse torque of the stator becomes the braking torque of the rotor. The value of this torque depends on the amount and pressure of the working fluid in the chamber (determined by the braking intensity level set by the control valve) and the rotational speed of the rotor.
We truck drivers all know what a hydraulic retarder is – it's a hydraulic retarder! This thing is installed behind the transmission and is especially useful when driving downhill on mountain roads. It works by stirring fluid to create resistance for deceleration, which is much safer than relying solely on brakes. Back in the days without hydraulic retarders, driving on mountain roads meant constantly pressing the brakes until your feet went numb, all while worrying about brake pads overheating and failing. With a hydraulic retarder, it's much easier – just flip the switch, and the speed drops steadily with almost no need to brake. After years of driving the Qinghai-Tibet route, it pains me to see new drivers not using the retarder. This thing can really save lives, and it saves several sets of brake pads a year too.
The hydraulic retarder, or 'liquid retarder' for short, is a device that uses the flow resistance of oil to slow down trucks. Simply put, it's a sealed chamber installed behind the engine containing an impeller. When activated, the liquid is rapidly agitated to create resistance, and this force is transmitted to the drive shaft to slow the wheels. I particularly like the smoothness of its operation, unlike the abruptness of traditional brakes. The longest I've used it was during a continuous 20-minute descent in the Qinling Mountains, and the hydraulic retarder held up perfectly—had it been just the brake discs, they would have been glowing red. However, new drivers should note that the hydraulic retarder doesn't completely replace brakes; you still need to use the brakes for sharp turns. In fact, many European imported trucks come standard with this device, significantly boosting safety.
