Patent GB-1069191-A (GB)
Title: Mechanism for driving a rotatably mounted member
IPC: B64C27/54
Filed: 1964-08-17
Abstract: 1,069,191. Folding helicopter rotor blades. BOEING CO. Aug. 17, 1964 [Aug. 26, 1963], No. 33490/64. Headings B7G and B7W. [Also in Division E2] A helicopter rotor is rotated to, and locked in a predetermined position before its blades are folded, and means are provided for rotating it to that position in the direction involving the lesser angular movement. A transmission shaft 83 is rotated through an hydraulic clutch 150 by a reversible hydraulic motor 148 until the plunger of an hydraulically operated lock 31 can engage a recess 153 in the shaft, the direction of rotation of the motor being determined by a control mechanism 32 actuated by a cammed surface 82 on the shaft 83. The distribution of pressure fluid is controlled by a valve 10, and the operation is initiated by energizing a solenoid 16, moving a valve 21 to the right and allowing fluid to flow from a pump 24 to the mechanism 32, and to engage the clutch 150. When the shaft 83 has been rotated to the predetermined position, the engagement of projections 103, 104 actuates a switch to de-energize the solenoid 16, rendering the mechanism 32 and clutch 150 inoperative, and energizing the solenoid 14 to move the spool 12 to the right allowing fluid to actuate the lock 31. The system is returned to its initial condition by energizing a solenoid 15, moving the spool 12 back to the position in Fig. 1, in which pressure fluid releases the lock 31. The control mechanism 32 (Fig. 4, not shown) includes a distributing valve comprising a spool (65) mounted within a sleeve (55), both urged away from the shaft by springs (53, 77) and urged towards the shaft when the solenoid (16) (Fig. 1) is energized, by fluid introduced into a chamber (64), until rollers (79, 89) (the latter being adjustable) on the spool and sleeve, respectively engage a cammed surface (82) and a cylindrical surface (not shown) on the shaft (83). The difference in the local radii of these two surfaces determines the relative positions of the spool and sleeve and hence which of the hydraulic motor connections (47, 49) is connected to the inlet (113, 51, 50) of the valve, and which to the outlets (43, 44, 45). The chamber (113) is supplied with fluid through a delay mechanism (in the lower part of Fig. 4), so that fluid is not supplied to the distributing valve until the rollers (79, 89) have contacted the cammed and cylindrical surfaces. The inlet of the control mechanism (32) is connected to the chamber (64), as previously stated, and to chambers (108, 136) in the delay mechanism. Pressure in the chamber (136) moves a piston (129) until a flange (142) on it opens a valve (124), allowing fluid to act on a further piston (123) to open a valve (117), allowing fluid to flow from the chamber (108) to the chamber (113). The delay is variable by adjusting the compression of the spring (120) closing the valve (117), and by adjusting a restriction upstream of the chamber (136). The lock 31 has connections (154, 155, Fig. 20, not shown) leading to connections 28, 29 respectively in the valve 10 (Fig. 1), and to chambers (163, 169) respectively in the lock. The lock also comprises a stationary member (158) with a flange (162) defining with the plunger (152), to which is fixed a flange (168), the two chambers (163, 169). The plunger is held in its two extreme positions by retainers (174, Fig. 22, not shown), each comprising an arm pivoted on the member (158) and mounting a spring-loaded arcuate based plunger (176) engaging a corresponding recess in the plunger (152).