He should then stay off the throttle long enough to allow the dog ring to engage with the next gear. With no assistance from the engine management, the driver must lift off the throttle sufficiently to allow the dog ring to be pulled out of engagement. The damage can usually be felt by the driver. Otherwise the engine will be reinstated during partial dog engagement, causing damage. With this system it is especially important to move the lever as fast as possible. A `cheat` version of this is to shift on the engine rev limiter, which can work well. This system is almost as good as an automated one as long as the driver pulls the lever very quickly. This system produces zero dog wear when set up well, and highlights the advantages of minimising gear shift time. The movement of the dog ring is powered and the engine is cut / re-instated in a co-ordinated manner. These are in order of shift method preference. We list below the different methods of up-shifting that are used in racing most commonly. We always recommend lightweight yet solid rod linkage, as opposed to cables. If a driver moves the gear lever slowly, or if the linkage is not rigid and effective, dog wear will occur. Therefore this period must be made as short as possible. The damage can only take place when initiating contact during a shift (the `danger zone`). It should be remembered that it is not possible to damage the dogs when fully engaged (in gear). (The opposite is true of a synchromesh gearbox as used in passenger cars, where slow movement helps). Successful up-shifting (defined as fast and non dog-damaging) will be achieved by fully moving the dog ring as rapidly as possible from one gear to the next, preferably with the engine's driving load removed until the shift is completed. This includes the gear linkage in the chassis. As a broad guide, the oil quantity and type that runs coolest tends to be the most efficient at lubricating and minimising power loss.įor successful gear shifting, remember that it is critical to ensure that all mechanical elements between the drivers hand and the dog faces are in good order and properly set. When you have established a pattern of gearbox temperature for your vehicle, you can then try different oil quantities and then different oil types. This can detect a big failure before it is catastrophic.Ģ. An above normal temperature indicates a gearbox fault (usually bearing or tooth failure etc.). There are two reasons for logging oil temperature:ġ. a cold wet day will produce cooler gearbox temperatures. The ambient temperature and the loads through the gearbox will affect temperature, i.e. Please note that it usually takes at least 15 minutes of running to reach a level maximum temperature. Monitor the oil temperature and note the pattern of temperature increase and the top temperature achieved. However, we would always offer the following advice to get the most from your transmission:įit a temperature sensor from your data acquisition system into either the gearbox sump area, or into the oil pipeline on a pumped oil system. Hewland do not currently recommend a specific brand of gearbox oil. Hewland Engineering Ltd is frequently asked to recommend oil types or brands for its transmission systems.
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