In general, slip gets worse as differential pressure increases, as viscosity decreases, and as gears wear. Depending on flow required, the pump should be rebuilt in 100 to 800 hrs. Flow and pressure drop off at about the same rate. The pump should last roughly 500 hrs. longer. In the case of variable speed systems, loss in flow is restored by increasing pump speed.
Flow is maintained for quite some time.
The hours stated above are just ball park estimates. This floating cavity concept allows the pump to maintain near zero slip throughout gear life due to its ability to adjust to gear wear. The shoe is held on the gears by discharge pressure and the suction port is located directly underneath the shoe. Both the suction shoe pumps and the cavity style pumps are among the most well designed pumps in the industry. Each one has its own strengths and its more favored applications.