Driven rotor Inlet Outlet Drive gear B C A E D Swashplate Cylinder block The fluid from here flows through the valve plate slot Inlet valve plate slot Drive shaft Outlet valve plate slot Piston Outlet port Inlet port Figure 12-25.  Axial inline piston pump. Figure 12-24.  Gerotor pump. with female splines in the pump drive shaft. Pump drive  couplings are designed to serve as safety devices. The shear  section of the drive coupling, located midway between the  two sets of splines, is smaller in diameter than the splines.  If the pump becomes unusually hard to turn or becomes  jammed, this section shears, preventing damage to the  pump or driving unit.  [Figure 12-25]  The basic pumping  mechanism of piston-type pumps consists of a multiple-bore  the purpose of mounting the pumps on the accessory drive  cases of aircraft engines. A pump drive shaft, which turns  the mechanism, extends through the pump housing slightly  beyond the mounting base. Torque from the driving unit  is transmitted to the pump drive shaft by a drive coupling.  The drive coupling is a short shaft with a set of male splines  on both ends. The splines on one end engage with female  splines in a driving gear; the splines on the other end engage  12-18