Hydraulic Pump Adapter

The ‘new’ grapple truck needs an auxiliary engine to drive the pump.  The easiest thing to do is simply drive the pump off the truck engine by way of the transmission PTO, but that is far more power (and fuel) than the job requires.

The easy way is not always the best way…

This part of town is just lousy with Detroit Diesels at this time of year.  This is a Rockford snap clutch on a ready and willing 3-71.

This is the double stack Permco that drives the loader.  The mounting surfaces of the clutch and pump are not directly compatible.  The clutch has a 4″ pilot with bolts 3.5″ on center, while the pump has a 5″ pilot with 4.5″ bolt centers.

Cut preliminary slug from clutch side plate.  I’m trying something different here, as the lathe spins a little slower than the Bridgeport.  The tool overhang is excessive, but I’m not in a rush.  For some reason, the cutter head is not fully seated in the turret tool holder…

Bore to just under 4″.  The cut is furry on account of a chipped carbide.

Cut the slug from the pump end plate.  This was slightly more involved, as this plate is .750″, and the cutter will only cut to 5/8″.  The cut was started from one side, then finished from the opposite side after flipping the plate.  Also, the cutter head is now seated in the tool holder.

Bore the center to match the other plate, and then bore half the depth of the pilot bore.  This cut is much cleaner, as I took the time to rotate the carbide.

A slight press fit facilitates both alignment, and fixturing for welding.



Parting off.  The excess length served to provide adequate chuckage whilst finishing the pilot bore , and then facing the pump end plate.  This work is a little too big for the worn out South Bend, which explains some of the chatter in the cut.

Facing the clutch end, and trimming the pilot to length.

Transferring the bolt holes.

The four black dots are blind hole transfer punches, or ‘spotters’.

Just a pinch will do ya’.  The punch marks for the clutch end are just barely visible on the right hand face.

Drilling the pump end.

The more or less finished product. Tight clearance dictates socket heads on the clutch end.

And now a well earned nap.