Patent ID: 8414454

Claim:
A change speed control system for a work vehicle, the system comprising: a hydrostatic type continuously variable speed change device effecting a change speed operation of power from an engine of the work vehicle and transmitting a resulting power to drive wheels, the continuously variable speed change device including: an axial plunger type variable displacement pump having a pump swash plate; and an axial plunger type variable displacement motor having a motor swash plate; a control device controlling the variable displacement pump and the variable displacement motor; a swash plate sensor detecting an operation position of the pump swash plate and inputting the operation position into the control device; and a switching mechanism switching the motor swash plate between a high speed motor mode in which the motor swash plate is set to a high speed position thereof and a low speed motor mode in which the motor swash plate is set to a low speed position thereof, wherein the control device is configured to perform a speed reduction control process for switching the motor swash plate from the high speed motor mode to the low speed motor mode, and wherein the control device is configured to perform, as a preprocess prior to the speed reduction control process, a pump speed reduction process for operating the pump swash plate to a target speed reduction position from a current position which is stored as a stored position, and during the speed reduction control process, the control device is configured to simultaneously perform a return process for returning the pump swash plate to the stored position.