Water does not compress, and something has to give, the rod is bushed and all of the pressure then ends up on a roller
If the manufacturers would use a roller bearing with out a retainer instead of a ball with a retainer they would never wear out
The bearing inside diameter would be larger so the crank could be larger and therefore the amount of air flow could be increased !!
Uhh, Never mind .... Where is that number to Boca ??