If the friction had not been so great, the pump would not have been damaged.
如果摩擦力没有那么大的话，这台泵本来是不会坏的。
2
Pipe friction is the resistance to flow caused by the pipe. As a general principle, it is better to use the largest practical pipe size to avoid losses in pump performance.
A lot of study showed that the friction of the ball friction coupling between piston and slipper obviously affected the life-span and the performance of the axial piston pump.