This three-part series proves: “No two valves are the same”!
The pilot control of directional spool valves and transmission valves, which is one of Thomas ventile’s main areas of application, has already been presented in the first two parts. The third and final part is dedicated to the control and regulation of axial piston pumps.
Axial piston pump for the closed circuit
Compact controllable tandem axial piston pump with swash plate system, for use in hydrostatic drives in closed circuits, electro-proportional control with PPCD04-NG valves
Image: courtesy of HANSA-TMP S.r.l., Italy
Hydraulic valve pumps: using axial piston pumps to boost efficiency
Axial piston pumps can be used in any number of areas, from hydrostatic drives in machinery through to setting the flow rate in working hydraulics. The demands placed on adjusting the angle of the swash plate in axial piston pumps in closed and open circuits are very different. The required flow rate changes rapidly in open-circuit applications, which typically supply a range of hydraulic functions. Valves here therefore need to set the required volume flow very quickly and precisely. In closed-circuit applications, meanwhile, which are often found in traction drives, the valves set the flow rate for the hydraulic traction motor fairly slowly, as the flow rate determines the travel speed and thus ensures that the machine starts up smoothly. Thomas’s valves are perfectly matched to the individual application and set the exact flow rate that each requires, a factor that is especially important in applications where the right and left drive sides are supplied by two different pumps (and where “synchronization” is very much the watchword). Although a degree of deviation in the synchronous actuation of the two pumps is unavoidable, the amount of this deviation will determine the machinery’s performance.
If it is too large, the machinery will go round in circles rather than drive straight ahead, particularly at low speeds. Small bulldozers are a good example: The smaller their pumps are, the more precise their control has to be. This is where Thomas and its valves really come into their own, especially regarding the stringent reproducibility requirements among the various valves combined with high quality standards.
Production according to automotive standards
Thomas manufactures to automotive standards in terms of cleanliness and quality in the off-highway segment too. Its entire production process is traceable, measurable, and dedicated to continuous improvement. Thomas’s customer-centric approach is focused squarely on reliable processes, low reject rates, and a high level of delivery reliability, both in Germany and further afield.
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