diesel fuel pump drive system

hi,
currently i am working on a high pressure fuel pump i have questions regarding the drive systems for the pump.

I am aware that the pump is driven by the crank shaft of the engine but how the reduction in rpm is attained is unknown to me. the rpm of the engine that i am working on is 1500 approx and the pump runs at 700 rpm approx. how do i achieve the reduction in the rpm using belt drive system. i require specifics such as the pulley pitch diameters for crank shaft and pump, belt length distance, how can i calculate these?

Pulley drives speeds are calculated by circumference. A driven pulley with half the circumference will rotate twice as fast as the driving pulley because one rotation's worth of belt on the drive pulley would pass twice over the driven pulley.

With a cogged belt drive the ratio calculation is similar to gears- you count the teeth. A 5 tooth driven pulley moves at 2X speed with a 10 tooth drive pulley.

Since you're looking for half-speed the driven pulley will need twice the circumference or twice the number of teeth as the driving pulley.

If you're using a distributor pump or a pintle pump to directly feed passive injectors, you will need a method of adjusting the pump for injection timing and having a cush drive on the pump will greatly lengthen belt and pump life. If you're using a constant pressure pump and electronically fired injectors you don't need a cush drive as the pump load oscillations will be far less.

Phil

Thanks for the reply phil, by the way I am using a crdi system.

You lost me at CRDI. I know belt drives and my diesel injection knowledge came from employment and extra training with Lucas CAV back in the mid 80's plus shop experience with VW, Peugeot, and Volvo diesels of that era. The rest of what I know about diesels is bits and pieces I learned from other mechanics along the way. I understand electronic injection basics- it's pretty much the same theory as with gas (petrol), just higher pressures and different mixture adjustment inputs.

Just curious about your project, what are you attempting? It seems you're either changing pump location or designing a new system.

Phil

Thanks for showing interest in this topic. I am an undergraduate student and my universities automotive lab is not well equipped. we have a conventional single cylinder kirloskar diesel engine and I am trying to install CRDI system on this engine I have all the necessary equipment such as the fuel rail ,solenoid injectors, high pressure pump.I am trying to connect the crankshaft and the pump using a belt drive system externally your tip is to use a toothed belt but what kind of gear pully should I use?