Automatic control system for hoisting machine

摘要

1,010,297. Winches; tower hoists. S. T. BUCK. Aug. 30, 1962, No. 33406/62. Headings B8B and B8H. A winch drum 18, Fig. 4, mounted on a portable tower hoist is driven from a motor 10, having an idling speed and a working speed, and coupled through electrically controlled clutch means 15 incorporating " up " and " down " driving elements which are automatically disengaged when the lifting means reaches predetermined positions. An electrically controlled brake unit 16 is geared to the drive system and is automatically disengaged with operation of the clutches. The brake unit 16 is coupled to a centrifugal over-speed governor 58 which operates during lowering to energize the " up " clutch device to provide additional braking. A tensioning device 27 is also provided for the cable 6 and operates to disconnect the clutches in the event of slackness or breakage in the cable. The clutch units (not shown) are associated with separate drive shafts 33, 48, Fig. 5, having oppositely rotating pinions 44 and 49 in engagement with a large pinion 29 on the winch drive shaft 17. The main housing 14 for the pinion 29 and clutch units is pivotally mounted on the shaft 17 and is adjustable angularly by a turnbuckle 28 for tension adjustment of the drive belt 12 from the motor pulley 31. The electrical push-button starting system incorporates a time delay device whereby engagement of the clutches is prevented before the solenoid operated motor throttle lever 89 has been actuated to bring the motor from its idling speed to its working speed. The control incorporates limit switches 65, 67, Fig. 14, actuated by adjustable nuts 60, 61 on a threaded shaft 59 mounted in a housing 22 and driven from the winch drum 18 through a chain drive 20, 21. The nuts have peripheral grooves 60 for adjustable engagement by a spring-loaded locking bar 63 and may be set so that the winch is stopped at any required upper and lower position. A third limit switch 69 may be incorporated for actuation towards the end of the downward movement of the hoist and operating to reduce the motor speed. Reference is made to the use of the winding apparatus on a tower hoist which is hinged in three sections 2a, 2b, 2c, Fig. 2, and which are collapsed for transporting. The hoist frame 1 also has retractable wheels 9. Supplementary drums 25, 26 may be used for power take-off and for raising and lowering the tower sections.