hi all
a newbie here,i am a diesel mechanisc with electric hyd experience needing a bit of info.
i have a komatsu d 50 dozer with a u/s engine but to get a new one is cost prohibitive.i have a same horsepower going engine but a differing bellhousing etc.
so to do away with the clutch system what size pump and motor would i need to run a 14 ton,100hp dozer through exsisting 4 speed trans.
i guess top revs needed would bearound 800/1200.
would cooling be a problem?
thanks

hi
maybe i have not explained properly.....
a 100 hp diesel should drive a rexroth a71 v pump or similar,so at 1000 revs i would have 71 lpmin,ok so what size motor ...hyd...would i need to drive a manual type gearbox which in turn drives a 14 ton dozer?

You would want to use a closed loop hydrostatic drive, with the pump controller modified to be unidirectional. Something like a rexroth A4VG pump and an A6V motor, but if the price of an engine was prohibitive, the price of this drive will be as well. Look around for a machine being dismatled.

thanks doug
why would the pump controller need to be unidirectional,as the transmission i intend to drive has 4 forwards and a reverse.
as i work in the mining industry often pumps etc surface at reasonable prices,would for example two commercial gear pumps,one as a pump and one as a motor,work.i could use exsisting resovoir and simply add a relief and a control valve.
you see the part that i find hard to understand is motor size to turn a large transmission at around 1000rpm.i have an asst of old gear pumps from lift/hoist systems in machines capable of a 20 t lift running around 3000 psi press.

so thanks for any input.

You need a closed loop, or hydrostatic drive in order to maintain engine braking ability. It will also provide a smooth transition from nuetral to drive. It needs to be unidirectional as you are going to be using the reverse function in the transmission. Most transmission are only designed to take input torque in one direction.
If there is an overall efficiency loss of 20% at the pump and another 20% at the motor, you are going to introduce 40 HP of heat to your existing system. If you want a 1:1 drive, figure out how much torque your engine puts out, pick a peak operating pressure you want to run at, size your motor displacement based on those numbers.
lbs/ft = in3 * PSI/(24*Pi)
lbs/ft = HP * 5252/RPM
Then to maintain a 1:1 ratio, your pump will have to be sized at least 10% larger to make up for flow losses.
Wouldn't it be easier to make a nice arificial reef out of that dozer?

This message has been edited. Last edited by: Doug Hanson,

thanks doug,i shall check out eng specs etc,
and the dozer will clear my remaining 30 acres then be sold.there are enough reefs here already.

hope your still there doug.
the new engine puts out at 1800 rpm 530 ft lb of torque and 180 hp,the top revs are 2600 but 1800 rpm seems to be the top of the torque curve.so heres hoping a canadian guru can do the math for me.
cheers

quote:

...do the math for me

Just use the equation posted previously, at least give it a shot. If your wrong, I'm sure someone will jump in to help.