Crane used high-pressure automatic control variable motor hydraulic motor transformation, its initial displacement of the smallest displacement, the output torque and the minimum speed the fastest, not artificially control the speed of the hydraulic motor maintenance, to meet the majority of the mechanical slow smooth start, in particular When starting the crane as a liter motor, when the weight in air travel after the second lifting of the moment, because of the small motor output torque can not lift heavy weights and the emergence of the phenomenon of falling seriously affect safety, is lifting machinery taboo. The use of a simple pilot pressure control, although the operator can easily be controlled motor speed, but it is difficult to accurately perceive the situation and make a quick motor load operation. In order to ensure the safety of the operator, only to motor slow work, but reduces the efficiency of machinery. 3. Relationship constant pilot pressure control and constant voltage control between the control priority to the pilot pressure control of the hydraulic motor maintenance, pilot pressure control and constant voltage control can not be performed while the motor control of the hydraulic motor, the motor constant working pressure below the set pressure , the motor will be entirely provided by the pilot pressure control system; when the motor operating pressure reaches the set pressure constant, constant pressure control servo valve motor will be automatically controlled. Hydraulic motor hydraulic motor installation _ _ Jing Chong hydraulic preferred by the Jinan Jing Chong Hydraulic Machinery Limited. Jinan Jing Chong Hydraulic Machinery Co., Ltd. (www.jnjcyy.com) (www.jnjcyy.com) strong, credible, in Jinan, Shandong mining machinery industry has accumulated a large number of loyal customers. The company better work attitude and constantly improving innovative ideas will lead crystal create hydraulic and you hand into the brilliant, for a better future!