초록 ▼

A method for the power-shiftable change-over of a hydrostatic vehicle drive of a mobile construction machine, comprising at least one hydrostatic capacity pump, a hydrostatic drive motor and a two-stage power-shift transmission, which drives the axle(s) of the construction machine via its drive shaf

A method for the power-shiftable change-over of a hydrostatic vehicle drive of a mobile construction machine, comprising at least one hydrostatic capacity pump, a hydrostatic drive motor and a two-stage power-shift transmission, which drives the axle(s) of the construction machine via its drive shaft, wherein the power-shift transmission is shifted with a change-over valve, which method is to be modified such that an operationally safe automatic change-over in dependence on the load is possible between the shifting stages of the power-shift transmission. This object is achieved by activating a switch (7), which causes at least two pressure switches (3, 4) that are operatively connected to at least one switching element (5) to be successively activated with different hydraulic contact pressures for the load-dependent automatic change-over of the power-shiftable transmission (1), wherein the switching element (5) is activated by one or the other pressure switch (3, 4) in dependence on preset load conditions in the hydraulic circuit and this switching element then electrically actuates the change-over valve (6) in order to effect the change-over of the power-shift transmission (1).

대표청구항 ▼

1. A method for a power shiftable change-over of a hydrostatic vehicle drive of a mobile construction machine with at least one axle, said vehicle drive having at least one controlled hydrostatic variable displacement pump, a hydrostatic drive motor, a hydraulic circuit, and a powershift transmissio

1. A method for a power shiftable change-over of a hydrostatic vehicle drive of a mobile construction machine with at least one axle, said vehicle drive having at least one controlled hydrostatic variable displacement pump, a hydrostatic drive motor, a hydraulic circuit, and a powershift transmission with at least two stages to propel the at least one axle of the construction machine, said hydrostatic drive motor comprising at least one of a fixed displacement hydrostatic drive motor and a variable displacement hydrostatic drive motor, wherein the transmission is shifted with at least one of pneumatic pressure, hydraulic pressure, and electric voltage and via at least one change-over valve, the method comprising:activating a switch by the operator; actuating a switching element with at least two pressure switches with differing contact pressures dependent on preset load conditions in the hydraulic circuit; electrically actuating the change-over valve with the switching element; activating a relay with an output of a vehicle speed monitoring frequency dependent switch, wherein the relay is closed by the frequency dependent switch at frequencies higher than zero to allow a shifting into second gear; creating a voltage signal in a predetermined frequency window by another output of the frequency dependent switch and feeding the voltage signal via another relay in an operative connection of the switch and the relay to the change-over valve to actuate a shifting of the transmission.