Frictional behaviour of different lubricants in an oil lubricated front fork bushing and steel tube contact

Motorcycle front forks along with the rear suspension determine as to how the motorcycle reacts to bumps and holes in the ground. It is vital that the movement of suspension parts is fast to enhance the rider's feeling of how the motorcycle is going to respond so that the rider can react accordingly, allowing higher speeds. In motorcycle front forks, the resulting forces from driving on uneven ground will push the damper both in its moving direction and in the non- moving direction. In the non-moving direction the friction will be highly dependent on the forces, materials, lubricants and dimension of the contact. Because of the friction in the forks, the driver’s input on how the motorcycle is behaving will decrease. This problem has been approached by measuring the friction between the surfaces of a polymer bushing and chrome-plated steel tube, using different oils at various temperatures to lubricate the contact. Additionally, the influence of different pressures and speeds has also been studied. The studies have shown that friction decreased with increasing pressure. Velocity influence studied indicated that the friction didn't change much during the tests. When the temperature influence was investigated, it was found that the friction value decreased for all oils up to a certain level. However, at higher temperatures some oils have shown higher friction and wear severe and the tests had to be aborted. This thesis work has only begun scratching the surface of this problem and further studies will be required to fully understand the frictional phenomena involved. However, some conclusions can be made from the work carried out so far. Oils that were tested tend to lower the friction between the chrome tube and Teflon bushing when the pressure and temperature are raised. Too high temperatures however, proved to be bad as some of the oils resulted in very high friction and wear. The speed has a lower impact on the friction values.Validerat; 20101217 (root