CABLE 1U9484 - Caterpillar

Illustration 1 g06323899
(1) Steering and transmission controls
(2) Hystat pumps
(3) Fan pump
(4) Final drives
(5) Hystat motorsThe hydrostatic power train is a dual path hydrostatic transmission with high pressure, closed drive loops.The drive loops consist of a piston pump with a rotating group for each track and a separate piston motor for each track. The piston pump is an overcenter pump provides oil flow for both forward and reverse travel. Travel direction is determined by the direction of flow from the piston pump. The piston motors are infinitely variable and provide a range of ground speeds. The piston pump also affects the ground speed of the machine. First, the pump upstrokes to provide the desired speed. The motors will destroke if more speed is commanded.The system also provides engine overspeed and underspeed protection. In an overspeed condition, the system automatically adjusts the current that is supplied to the hydrostatic transmission pumps and motors to slow the machine. Engine underspeed protection is provided by decreasing the control currents to the hydrostatic transmission pumps and motors. This protection is in response to the low engine speeds and to the engine lug.