1. A cam chain tensioner comprising a transmission chain; a tension adjusting assembly, housing an oil chamber receiving oil through a pump from the engine oil sump; said chamber accommodating a plunger provided with a roller at its end, said roller' resting on the said chain under pressure of the oil, in the chamber, acting on the plunger, the pressure increasing and decreasing with the pressure of the oil in the chamber and, therefore, with the speed of the engine, whereby the tension of the chain is provided by the roller and plunger, dependant on the speed of the engine, at all times when the engine is running. 2.. A cam chain tensioner substantially as herein described with reference to, and as illustrated in, the accompanying

This invention relates to a cam chain tensioner. Conventionally, chain tension is achieved through a chain tensioner (chain rubbing over a flat surface) and a spring loaded adjuster assembly. This tensioner exerts a constant load on the chain independent of engine speed, leads to disproportionate load on the chain and high frictional loss.
The chain tensioner proposed herein will reduce the chain-to-tensioner friction by bringing in rolling contact with the chain as against the existing sliding contact. Furthermore, in the tensioner proposed herein the chain tension is automatically adjusted by the oil pressure on the plunger which is related to the engine speed,
This invention will now be described with reference to the accompanying drawings which illustrate, by way of example, one of possible embodiments of the chain tensioner proposed herein.

A chamber C receives oil from the engine oil sump by

means of the pump P. The said chamber accommodates a plunger T. The end of the plunger is provided with roller R which rests on the chain.E. The oil in the chamber C exerts pressure on the plunger T which is related to the pressure of the oil in the sump whereby the roller R exerts an equivalent pressure on the chain E to tension it. As the pressure of oil in the engine oil sump increases or decreases with the speed of the engine the pressure exerted by the plunger T on the chain E increases or decreases correspondingly; Thus the chain tension varies accordig to engine speed without remaining constant as in the case of the known tensioner. Besides, the roller R keeps a low friction contact with the chain unlike the flat surface contact between the end of the plunger and the chain of the known tensioner.
It will be appreciated that various other embodiments of the tensioner proposed herein are possible without departing from the scope and ambit of this invention.

We Claim:
1. A cam chain tensioner comprising a transmission chain; a tension adjusting assembly, housing an oil chamber receiving oil through a pump from the engine oil sump; said chamber accommodating a plunger provided with a roller at its end, said roller' resting on the said chain under pressure of the oil, in the chamber, acting on the plunger, the pressure increasing and decreasing with the pressure of the oil in the chamber and, therefore, with the speed of the engine, whereby the tension of the chain is provided by the roller and plunger, dependant on the speed of the engine, at all times when the engine is running. 2.. A cam chain tensioner substantially as herein described with reference to, and as illustrated in, the accompanying