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Wheel change
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Video Transmission
Video Gearbox-gripes
Video History 1
Video History 2
Video Var. Speed Gearbox 1
Video Var. Speed Gearbox 2
Video Var. Speed Gearbox 3
Video Var. Speed Gearbox 4
Video Var. Speed Gearbox 5
Video Light commercial veh.
Video Shift Possibilities
Video Gearshift Lever
Video Transmission (truck)
Video Ecosplit Gearbox
Video Gearshift (truck) 1
Video Gearshift (truck) 2
Video Truck Multi-axle Gearbox
Video Group/Splitter Gearb.
Video Gearbox Lubrication
Video Axilliary Drive
Video Retarder 1
Video Retarder 2
Video Retarder 3
Video Overdrive
Video Synchronising 1
Video Synchronising 2
Video Two-Shafts Gearbox
Video Gearbox (de)mounting 1
Video Gearbox (de)mounting 2
Video Front - Cross-engine
Video 3 Shafts (not coaxial)
Video Gear Shaft
Video Transmission Design
Video Tractive Power
Video Direct Shift Gearbox 1
Video Direct Shift Gearbox 2
Video Direct Shift Gearbox 3
Video Form. 1 Transmission
Video Motorcycle Gearbox

Video Transmission Ratio
Video Three-shafts Gearbox
Video Two-shafts Gearbox
Video Gear Spreading

Video Manual Gearbox 1
Video Manual Gearbox 2

          A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



It's quite possible, that drivers of modern trucks don't even notice the presence of a retarder at all. Previously, they had to be consciously operated by a seperate switch, now they switch themselves on with a light tap on the brake pedal. Thus it's job also becomes obvious, with reference to to the permissible gross weight, to relieve the, not stable enough, foot-brake during prolonged use.

Retarder saves at certain speed range brake pads.


The retarder also supports the engine-brake. It is found, as a primary version, on the drive shaft, and as a secondary version, on the gearbox output shaft (see picture). Because it is not seperatly, as an independent block mounted behind the gearbox, but rather integrated into it, the above shown secondary retarder is also known as an 'intarder' (in-board and same lubrication source as the gearbox). The primary retarder brakes particularly well at high engine RPMs which is, e.g., important for the very often low speed operation of city-busses. As opposed, the secondary retarder relates directly to the wheel speed, and is thus, more suitable for long-distance haulage.

It converts, when required, kinetic energy into heat. One could compare the hydraulically operated retarder with a torque-converter without a guide wheel, whose turbine-wheel is solidly connected with the casing. Thereby, it's the response time which is important. Through a special valve working at certain intervals, the retarder is partly or completely flooded , depending on the necessity, the more it floods, the greater the braking effect. To ensure that it operates quickly, seen on the right of the picture is a large reservoir of pressurised gearbox-oil waiting to be used.
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2001-2015 Copyright programs, texts, animations, pictures: H. Huppertz - E-Mail
Translator: Don Leslie - Email:

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