why Hollow vs full pistons in variable pumps and motors
why Hollow vs full pistons in variable pumps and motors
(OP)
Hi all, my students asked me why some pisons in carbiable piston pump motors and pumps are hollow, and why others are full.???
I have a couple of ideas why, but I'like input on this as some people have mentioned its just the way it is, but I honestly think that manufacturers won't spend extra money on machining a hole in the piston or pay for extra metal if it does not serve a purpose.
I was think hollow type pistons might decrease the the rotating mass (inertia) of the rotating group (cylinder block and pistons) but......
Thanks a lot
I have a couple of ideas why, but I'like input on this as some people have mentioned its just the way it is, but I honestly think that manufacturers won't spend extra money on machining a hole in the piston or pay for extra metal if it does not serve a purpose.
I was think hollow type pistons might decrease the the rotating mass (inertia) of the rotating group (cylinder block and pistons) but......
Thanks a lot





RE: why Hollow vs full pistons in variable pumps and motors
I'm sure that the reduced mass helps keep the shoes on the swashplate at high speeds, too.
Mike Halloran
Pembroke Pines, FL, USA
RE: why Hollow vs full pistons in variable pumps and motors
They are hollow to reduce material cost and to make them easier to manfacture...lube hole in the middle.
The trade off is in the higher inertia. The higher inertia provides a flywheel effect aiding pump stability.
Adrian
RE: why Hollow vs full pistons in variable pumps and motors
I also heard that most were made with Powdered Metal and that type production and tempering process worked better with less mass.
Probably just how a Draftsman from one company drew the first one since it looked good on paper.
Bud Trinkel, Fluid Power Consultant
HYDRA-PNEU CONSULTING