finding a pump that meets requirements

[sshep7]

Alright, here is the situation.

I was recently dragged into a project @ work once the originators realized their initial design wasn't going to work.

We are retrofitting a truck (18 wheeler) with a hydraulic power unit to feed power tongs for running drill pipe and casing.

The requirements of the system are

2500-3000 max psi (static), while capable of delivering 50-60 gpm @ around 500-1000 psi

These requirements must be met when the truck is @ idle. The truck idles at about 700 rpm, horse power is around 100, we need at least 100 to feed the system pump. Are there any pumps out their that can deliver such a large amount of displacement, yet are small enough to fit underneath a truck? Size requirements roughly a 3 ft X 3 ft area. I've already considered running 2 small pumps in parallel, and changing the gear ratio on my PTO (transfer case from motor to pump), but still I'm having trouble finding a pump that can come close to the GPM requirements.

Any help would be appreciated!!!!

 

[CRG]

Power tongs are not run continuously, and as such, it may be more efficient using a small pump with an accumulator. Has this been considered?

 

[sshep7]

yes, that's an option I've considered, since it mirrors most of our standard hydraulic power units. Our space confines will make installation more of an intensive effort, which is what i was trying to avoid.

Initially, we incorporated a pressure switch (with a 20-100 psi deadband)to control the truck throttle, and we came acceptably close to our GPM requirements, but with faulty logic. When the tong builds torque, pressure increases, the switch then signals the engine to throttle and increase rpm. The problem is when the tong is running with no or neglegible torque, we still want 50-60 gpm to rotate the tong @ full speed in high gear.

 

[CRG]

Consider a small accumulator with pressure switch and flow switch on the piping to the tongs. Throttle engine whenever pressure drops or there is flow to the tongs.

 

[aviat]

Some installations, like cement trucks and logging trucks, mount their pumps on the front bumper and have a shaft running to the engine. Maybe that is something else you can look into.