Abstract: A drive device for vehicles comprises: a drive prime mover, a power splitting hydrostatic mechanical transmission coupled with the prime mover and having a planetary differential transmission with at least four shafts and two groups of planet wheels, two sun wheels, a web and an annulus, two main shafts forming an input and output and connected with different shafts of the planetary differential transmission, a clutch two variable displacement hydrostatic machines which are respectively connected in at least one operational range with a respective shaft of the planetary differential transmission and are adapted to alternately operate as a pump and as a motor, a first hydrostatic machine which, when the second hydrostatic machine is stationary, being able to be switched over from the input main shaft to the sun wheel, not on the drive side, on transition from one to the other operational range by means of said clutch means and during traction operation is switched over from the motor to the pump function.

Abstract: In the case of hydromechanical power splitting transmission for vehicles the aim of the invention is to make possible the use of the same type of hydrostatic machine is hitherto and of an identical or similar four-shaft planetary differential transmission while at the same time expanding the effective range of conversion to cover substantially at least twice the range. This is achieved in that the hydromechanical power splitting transmission is designed for an extremely wide overdrive operation with a speed of rotation ratio (noutput: ninput of the two main shafts) of up to a maximum of 2. This is achieved by the addition of simple gear trains and the additional provision of clutches.