Twin lever control actuator
DESCRIPTION 
     1. Technical Field 
     This invention relates to actuating devices for flexible push-pull cables and particularly to actuators using a drive wheel to move the core of a push-pull cable. 
     2. Background Art 
     Prior push-pull cable actuators using a circular drive wheel have required bending of the cable core to coact with the drive wheel. Examples of such devices are found in U.S. Pat. Nos. 3,828,624 and 2,890,593. Another device shown in U.S. Pat. No. 3,160,027 uses a flexible belt to transfer both compression and tension loads to a cable core. 
     DISCLOSURE OF INVENTION 
     In one embodiment an actuator assembly for moving the core of a push-pull cable relative to its sheath has a control body supporting a central arm pulley and an idler pulley. The pulley cable carries an attachment device to attach an end of the push-pull cable core to the pulley cable between the pulleys. A support holds the core of the push-pull cable parallel to the straight run of pulley cable between the pulleys, thus providing linear actuation of the cable core with no movement of the sheath. The invention may also be practiced in a dual controller having similar mechanisms on opposite sides of the controller body. 
     In one aspect of the invention adjustable friction devices are provided for the pulley wheels to provide a force resisting rotation of the pulleys and thus control movement. In one form the friction device may be a ball detent while another form may be a friction pad. Both the ball detent and the friction pad may be interchangeable to provide flexibility in the application of the actuator assembly. 
     Other features of the invention include a mechanism for attaching the pulley cables to the pulley which also serves to adjust the pulley cable tension and a mounting arrangement which uses the mounting lugs to limit the control movement. Cams may be provided on the control pulleys to actuate electrical switches to provide interaction with the electrical system of the controlled device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the twin lever control actuator of the invention. 
     FIG. 2 is a sectional view in elevation of the control actuator of the invention. 
     FIG. 3 is a side view of the actuator of FIG. 1. 
     FIG. 4 is a partial sectional view along line 4--4 of FIG. 3. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Illustrated in the drawings is a dual lever control actuator 10 for operating the clutch and throttle of a remotely located marine propulsion device such as an outboard motor or a stern drive, not illustrated. The dual lever actuator 10 includes a control body 11 supporting two identical control arm pulleys 12 and two idler pulleys 13. Control levers 14 are attached to the control arm pulleys 12. A pulley cable 15 is mounted in the circumferential grooves 16 on each pulley of the pulley sets and is attached to the control arm pulley 12. A push-pull cable 17 is mounted on each side of the actuator 10 with its core attached to the pulley cable and its sheath attached to the control body 11 to provide linear movement of the core element. 
     The die cast aluminum control body 11 includes two end mounting lugs 20 and two side mounting plates 21 for supporting the actuator on any appropriate surface. The mounting arrangement includes two plastic base sections 22 having elements which fit under the mounting lugs 20 and plates 21 and are held in place by mounting screws 23 which pass through both the base sections 22 and the side mounting plates 21 to affix the actuator 10 to the appropriate surface. Projections on the base sections interlock with holes, not illustrated, on the plastic cover to removably hold the cover in place. 
     Two steel shafts 24 and 25 are force fit through the control body 11. The first of these shafts 24 supports the two control arm pulleys 12 for rotation and the second shaft 25 supports the two plastic (Delrin) idler pulleys 13. The idler pulleys 13 are retained in place by a bolt 26 and nut 27 extending axially through the tubular idler shaft 25. Two nylon bushings 28 serve as bearings for the control arm pulleys 12, and nylon washers 29 are used to separate the aluminum pulleys 12 from the control body 11. The control arm pulleys 12 are retained on the shaft by machine screws 30 which thread into the shaft 24 and bear on washers 31 and the nylon bushings 28. The control levers 14 are attached by splines 32 and set screws 33 to the control arm pulleys 12. 
     The two pulley cables 15 carried by the pulleys 12 and 13 are attached to the control arm pulleys 12. Each of the cables 15 has a male threaded fitting 34 and a plug 35, swaged on opposite ends. The plugged 35 ends are retained in notches 36 at the end of the pulley grooves 16, the cables 15 are looped around the idler pulleys 13, and nuts 37 are used to adjust the cable tension against the radial face 38 on the control arm pulley 12. Rectangular threaded stud blocks 39 are also swaged to the pulley cable 15 between the pulleys to provide a means for attaching the cores of the push-pull cables 17 to the pulleys cables 15. 
     To limit the rotation of the control arm pulleys 12, stops 40 are provided on the control body 11. The side mounting plates 21 project through the openings 41 in the control arm pulleys 12. Abutments or stop surfaces 40 on each end of the side mounting plates 21 coact with stop surfaces 42 on the control arm pulley 12 to limit the control arm pulleys to 90 degrees of rotation. The system of stops serves to limit the movement of the pulley cable stud blocks 39 to the straight run of pulley cable between the pulleys. 
     Conventional flexible push-pull cables 17 are connected to the actuator 10. The cable end has a rigid tube 43 at the end of the cable sheath and a rigid bar 44 at the end of the cable core coaxial therewith. Holes 45 in the flattened ends of the bars 44 fit on the threaded studs 39 on the pulley cables 15 and are attached with lock nuts 46 to prevent any lost motion between the pulley cable 15 and the push-pull cable core. A coupling barrel 47 affixed to the cable tube 43 fits into a bore 48 in the control body 11 with the cables passing through the slots 49 while a retainer plate holds the coupling barrel 47 in place to attach the tube 43 to the control body 11. Two attachment points are provided on each side of the control body 11 to permit flexibility in the use of the actuator 10. Ridges 50 are provided on the control body 11 parallel to the straight run of pulley cable to stabilize the push-pull cable ends under heavy loads. 
     Adjustable control loading is provided by friction devices housed in bores 51 in the control body 11, as shown in FIG. 4. A ball detent including a ball 52 and two concentric coil springs 53 and 54 may be used. The inner coil spring 53 is adjustably loaded by an adjustment screw 55 engaged with the control body 11. Access to the adjustment screw 55 is readily available since the housing extends through the slot 41 in the opposite pulley 12. The ball 52 is biased against a smooth cast surface 56, shown by dotted lines in FIG. 3, on the inner face of the control arm pulley 12. A detent notch 57 cut through the control arm pulley 12 provides the detent action. By using the adjustment screw 55 to control the spring bias on the detent ball 52, both the control load resisting the rotation of the control arm pulley 12 and the detent load may be set at a desired level. The detent is particularly suitable for use in controlling a gear shifter where a neutral detent is desirable. 
     Alternatively a nylon friction pad 58 may be housed in the bore 51 and loaded against the control arm pulley 12 by the adjustment screw 55. The friction pad 58 rides against the surface 56 on the control arm pulley 12 and is large enough to bridge the detent notch 57. Thus a desired uniform friction load may be provided against the control arm pulley 12 to provide a smooth control load suitable for an engine throttle controller, for example. This arrangement provides flexibility in application of the controller, since the control actuator may be easily modified to provide two throttle controllers, two shift controllers, or one throttle and one shift controller by merely installing the appropriate friction device. 
     Cam surfaces 59 are provided on the outer rims of the control arm pulleys 12 to activate electrical switches. For example, a neutral safety switch 60 could be controlled by the cam 59 when the control arm pulley 12 is used to control a gear shifter on an outboard motor. Such a switch would prevent starting the outboard motor engine except when the gear shifter is in its neutral position.