Hydrostatic torque converter having a stepped transmission

US4187739A · kind A · utility

Assignee

• Zahnradfabrik Friedrichshafen AG · DE

Inventors

• Karlmann Hamma · Tettnang, DE
• Anton Ott · Tettnang, DE
• Werner Vetter · Völklingen, DE
• Arun K. Chatterjee · Redmond, US

Key dates

• Filing date: Dec 13, 1977
• Grant date: Feb 12, 1980
• Expiry date: Dec 13, 1997

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T74/19163
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

A hydrostatic torque converter has a hydrostatic transmission and a stepped or gear transmission shiftable under load by selective actuation of respective clutches assigned to the gear trains. The variable-displacement pump is controlled hydrostatically to follow the switchover between clutches with the control pressure to the servocontrolling the displacement of the pump being regulated in response to the fluid pressures of the clutches through respective pressure modulation valves. As a consequence, the hydrostatic transmission compensates for the jump resulting from the shifting of the steps of the gear transmission and follows the stepping of the gear transmission outside the forced actuation of the transmission (positive switching overlap of the shifting clutches) in dependence upon the progress of load transfer from the released to the engaged clutch.