A power end frame assembly for a reciprocating pump that includes a first and second end plate segment each including annular bearing support surfaces configured to support a crankshaft bearing assembly. At least one middle plate segment is disposed between the first and second end plate segments and includes an annular bearing support surface configured to support a crankshaft bearing assembly. The annular bearing support surfaces of the first and second end plate segments and the at least one middle plate segment each have a diameter and are coaxially aligned. The diameter of at least one of the first and second end plate segments is different from the diameter of the at least one middle plate segment to facilitate insertion and removal of the crankshaft bearing assembly from the power end frame assembly.