Patent GB-602272-A (GB)
Title: Cable tension regulators
IPC: B64C13/30
Filed: 1945-08-24
Abstract: 602,272. Aircraft controls. DEHN, F. B. (Bofield Research & Development Co.). Aug. 24, 1945, No. 21801. [Class 4] [Also in Group XXXII] A tension regulator for a cable control system applicable to aircraft comprises a plunger B, Fig. 1, which is slidable within a hydraulic cylinder A and constantly urged to retracted position within the cylinder by a spring F, and a valve D movable in a chamber 2 in the plunger for controlling the flow of fluid through ports in the chamber from one side of the plunger to the other, the arrangement being such that the valve D is movable in the chamber to close momentarily the ports in response to the movement of the plunger in opposite directions so as to lock the plunger against rapid movement and maintain a predetermined tension on the cables which are attached to the cylinder A and plunger B respectively. The plunger B, which is provided with a skirt portion 12 having a screw-threaded connection with the rod 5, has a small orifice 15 at its rear end affording communication between the chamber 2 and the rear portion 1a of the cylinder ; the chamber 2 also communicates with the forward portion 1 of the cylinder by means of passages 16, 17 and a port 18. The valve D, which is loosely slidable in the chamber 2, has oppositely-disposed and axial portions 27, 28 coacting respectively with the passages 16, 15. Springs 29, 30 of equal tension are mounted on opposite sides of the valve so as to set the latter in position permitting a free flow of fluid between the opposite sides of the plunger. The plunger rod 5 is hollow and screw-threaded at its end for the connection of a cable-attaching member 7. At the opposite end, the cylinder is fitted with a screw-threaded cap E carrying a second cableattaching member 8. The rear end of the cylinder is fitted with a compensator C which has a recessed head 21 to receive the end portion 14 of the plunger and a rearwardextending skirt 22. One spring, or a pair of springs 23, 24, is mounted within the skirt 22 for urging the compensator forwardly in the direction of the plunger. The springs 23, 24 are more powerful than the spring F, and are arranged to keep the fluid in the cylinder under sufficient pressure and prevent leakage thereof. This compensator C takes care of any contraction or expansion of the unit or of the fluid therein, and prevents the formation of a vacuum in the cylinder. In use, the expansion or contraction of the cables and connections only causes the plunger to move slowly forward or rearward in the cylinder without causing the valve D to seat on either of the passages 15, 16, and the spring F constantly holds the plungers in retracted position and maintains uniform tension in the cables. If, however, a sudden intentional load should be imposed in the control system, the valve D moves in opposite direction to that of the plunger so as to overcome the corresponding spring 29, 30 and close one or other of the passages 15, 16 ; the fluid then starts to bleed slowly around the valve and the pressure in the chamber 2 gradually rises until the valve is again unseated. For effective operation, the control system is fitted with two regulators R, R<SP>1</SP> as shown in Fig. 8, wherein a control member O in the form of a pulley is attached by cables H, H<SP>1</SP> to the plunger rods 5 of the two regulators the cylinders A of the two regulators are connected by cables J, J with the controlled member O<SP>1</SP> which may be the rudder, aileron or other member. In the position shown, the operating member O has been moved in anticlockwise direction so as to locate the valve D of regulator R in seated position in the passage 15, and the valve D of the second regulator R<SP>1</SP> is seated in the passage. 16.