| 摘要 |
A servo-device, esp. for drilling tool drive systems, includes a hydraulic motor (1) with a variable speed controlled by controlled variable hydraulic pressure applied to the inlet of the motor speed and controller, the novelty being that this applied pressure is varied in a controlled manner by (a) a pressurised hydraulic fluid feed system (9); (b) a hydraulic fluid flow rate and/or pressure regulator (13) connected to the inlet of the speed controller (7); and (c) a device for creating a controlled variable pressure drop between the flow rate regulator outlet(s) and the speed controller inlet for controlled variation of the pressure applied to the speed controller (7). The device has two variable capacity motors (1) fed in parallel by the pressurised hydraulic fluid source (9), the inlet of the capacity controller (7) of each rotor being connected to the pressure drop device (16) which is pref. a flow rate or pressure limiter. A circuit selector (15) is located upstream of the flow regulator (13) and has two positions, i.e. a first or rest position, in which it connects the regulator inlet (e) to a hydraulic fluid reservoir (14a), and a second or operating position, in which it connects the regulator inlet (e) to the pressurised fluid supply (9). ADVANTAGE - The device is compact, allows remote monitoring of the rotational speed of a drilling tool, has simple construction and maintenance and is inexpensive.
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