Patent GB-741612-A (GB)
Title: Improvements relating to locking means for control devices
IPC: F16B1/04
Filed: 1953-03-16
Abstract: 741,612. Locking aircraft control levers. DE LACKNER HELICOPTERS, Inc. March 16, 1953, No. 7258/53. Class 4. [Also in Group XXIV] A lockable control device suitable for aircraft throttles or flaps comprises a pair of separate relatively movable members, means for releasably clutching said members together comprising a clutch release member mounted on one of said separate members and displaceable relatively thereto from a neutral position in which said members are clutched together and an offset position in which said members are declutched, and magnetic means for restoring said clutch release member to and normally holding it in said neutral position, against random external vibrations so that an external force-of determined direction and magnitude is needed to displace said clutch release member, thereby avoiding " creep." As shown in Figs. 1 and 2 a shaft 1 fixed to an aircraft structure has mounted on it an H-sectioned collar 15 prevented from axial movement by two anti-friction seals 11, 12 held in members 8, 6 locked on to the threaded ends of shaft 1 by nuts 7, 9. Between the web 19 of the collar and shaft 1 are two rollers 13 acted upon by springs 28 between a block 26 and two roller keepers 25, so as to wedge themselves between the shafts 1 and a wedge block 16 of greater radius of curvature than collar 15 and fastened thereto by bolts 34, so as to constrict the roller-way symmetrically. Also fastened to wedge block 16 and collar 15 by bolts 34 is a built-up lever 10 consisting of two plates 37 kept in spaced relation by spacers 38a and rivets 39, and of side members 40 bolted to spacers 38a by bolts 41. A clutch release member 36 pivoted on a pivot 43 lies between plates 37 and is actuated at one end by a pin 45 engaging a slot 44a, the pin being mounted on a member 42 pivoted to the lever at 45b and having a knob 45d. The other end of member 36 passes through a hole in wedge block 16, into a hole 30 in the roller release block 24. In operation, a force applied to knob 45d rocks member 42 and thus the clutch release member 36, which moves the roller release block 24 to unwedge one or other of rollers 13 against the action of the corresponding spring 28, to enable the collar to be rotated in the appropriate direction around the shaft under the force applied to knob 45d. Two horse-shoe magnets 49 with unlike poles opposed are secured to members 46 adapted to pivot on pins 47 and interconnected by teeth 48, and bearing set-screws 51 adapted to contact and centre the clutch release member 36 by virtue of the mutual attraction of the magnets 49. On release of the knob 45d the magnets, separated by displacement of the member 36, tend to move together and centralize the member. If the magnets are so far separated that their mutual attraction is insufficient, the restoring spring 28 will centre the end of member 36 until the magnets are sufficiently near each other. Block 26, collar 15, and a lever extension 32 are bolted together, the latter being pin-jointed to a control rod 35. In the embodiment of Fig. 10, a lever 57 is mounted on a pivot 56 to rotate relatively to a fixed quadrant 55 having a toothed arcuate rack 72 adapted to be engaged by the toes 70 of pawls 67, 68 pivoted to lever 57 on a pivot passing through a slot 63 in a clutch release member 60 pivoted at 61 to lever 57 and having a knob 95 at one end. A pin 75 on clutch release member 60 is adapted to engage one of the heels 73 on the pawls to disengage that pawl from the ratchet to enable the other pawl to ratchet in the appropriate direction in the usual way. A spring wound round the pawl pivot has its hooked ends 74 hooked on the pawls to press them normally into engagement with the ratchet. A horse-shoe magnet 76 is secured to a member 82 having arms between which is a peg 86 on lever 57, a spring 88 acting between the peg and member 82. A soft iron polepiece 79 is secured to the end of member 60 and has a projecting tongue 90 engaging the space 84 between the magnet poles. In operation, a force applied to knob 95 tilts member 60 on its pivot 61 until pin 75 engages one or other pawl to release it from the rack, enabling lever 57 to move by ratcheting the other pawl. When the force is removed the spring acting on pawls 67, 68 moves peg 75 towards the central position until the polepiece 79 is sufficiently close to the magnet to be moved thereby to centre the member 60. In the embodiment of Fig. 15, a lever 100 is pivoted at 101 to rotate relative to a fixed quadrant 103 having a track 111 adapted to be gripped between the poles 117, 118 of a horse-shoe magnet pivoted at 115 to a clutch release member 112, and a polepiece 128 rotatable and slidable under the action of a spring 136, relative to a peg 133 on member 112. In operation, deflection of member 112 relative to lever 100 moves the magnet to pivot about a peg 106 between its poles fast to lever 100 and working in a slot 116 in member 112, until it contacts a second similar peg 107. The magnet is thereby rocked until one of the rollers 125 contacts the track 111, declutching lever 100 from the track. Movement relative to the quadrant tilts the polepiece 128, compressing spring 136. On release of the moving force, spring 136 pushes the polepiece to recontact the track, centralizing the lever to a sufficient degree to bring the magnet close enough to the polepiece to enable the magnetic attraction to complete the centralizing. In the embodments of Figs. 10 and 15, a plurality of levers and quadrants may be mounted on a common shaft, being held in spaced relation by spacing collars and tie bolts, e.g. bolts 104, Fig. 15.