Valves play a central role in the hydraulic systems of construction and agricultural machinery by controlling fluids. However, there are a large number of different valve types that vary depending on the area of application. Although the valves appear identical on the outside due to the efficient design of the Thomas modular system, they fulfill specific requirements and customer wishes thanks to numerous variants. The main areas of application for Thomas valves cover three areas: the pilot control of directional spool valves, transmission valves for smooth gear engagement and the control and regulation of axial piston pumps. In this second of three articles, we look at clutch control valves.
Clutch control valve: PPCD09
Hydraulic clutch control: changing gear with gearbox valves from Thomas
The fast responses and precision of Thomas’s gearbox valves make driving a breeze thanks to jerk-free gear changes. This requires the highest degree of quality and a valve that is calibrated precisely to the respective application.
When changing gear in powershift transmissions, the clutch piston is pushed to just in front of the kiss point (the point at which the clutch disks touch) within no time at all. Contact pressure is then increased evenly and precisely on the first clutch and released on the second at the same time so that the gear change happens without any interruption to the load. It happens so quickly and precisely that the driver will barely notice the shift. The result is a smooth and seamless driving experience in which the vehicle responds in the best possible way to the driver’s input at all times and every shifting movement is perfectly in synch.
The PPCD08 and PPCD09 directly operated valves from Thomas are also the most compact clutch valves on the market, and the PPCD09 boasts the highest flow rate around at 30 l/min. The valves offer highly precise and stable pressure control, which ensures smooth switching operations. Their control pressure is immune to fluctuations in supply, making them easy to integrate into various customer systems.
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Most users will find what they’re looking for in our extensive range of directly controlled and pilot-controlled valves. And, for the few that don’t, our expertise makes us the go-to partner for customized solutions.
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