GB1037382A - Improvements in or relating to goods handling trucks - Google Patents

Abstract

1,037,382. Masted lift trucks. LANSING BAGNALL Ltd. Aug. 20, 1964 [May 20, 1963], No. 20014/63. Heading B8H. A masted lift truck is provided with a device for automatically stopping the lifting carriage at a height preselected from a set of predetermined heights. As shown in Fig. 1, the lifting carriage 15 is raised on the mast 14 by a nut 23, secured to the back plate 18 of the lifting carriage, and engaging a screw 21 rotatably mounted on the mast and driven by an electric motor 22. A cam cylinder 26, formed with a circumferential groove 38 and with vertical rows of indentations 39, is rotatable on a spindle 25, secured to the mast, by means of a control knob 29, through a flexible drive 28 and gearing in a casing 27, whereby different vertical rows of indentations 39 can be brought into alignment with the operating member of a switch 40 secured to the rear of the back plate 18. A housing 43 on which the control knob 29 is mounted, is provided with a rotatable cylinder 47 which is provided with ratchet teeth 48 and in which a cylinder 49, provided with a pointer 54 and cam 52, is rotatably supported. The cylinder 49 is releasably held in the cylinder 47 by a spring-loaded ball detent in positions corresponding to the positions of the indentations 39 on the cam cylinder 26. A preselector switch 42 on the housing 43 is opened when the cam 52 engages the operating member 53. In operation, the cylinder 49 is turned by means of a knob 157 until the pointer 54 is at a point on a scale on the housing 43 corresponding to the height to which the lifting carriage is to be raised. The electric control circuit, Fig. 6 (not shown) is such that when the lifting carriage is rising, the switch 40 closea when the operating member engages each indentation 39 thereby actuating a solenoid associated with a pawl engaging the teeth 48 to turn the cylinders 47, 49 through one step. At the selected height, the cam 52 engages the operating member 53 and opens the switch 42 thereby stopping the motor 22. When the truck is used for depositing loads on shelves, the cam cylinder 26 is raised slightly on the spindle 25, thereby raising the preselected heights to allow the forks to clear the shelves and to lower the load on to the shelves. The cylinder is raised by a yoke engaging a groove at the lower end of the cylinder and adapted to be raised by a lever 37. In a second embodiment, Fig. 9 (not shown), the truck is provided with a telescopic mast 80, 81 and a chain 87 passes from the bottom of the fixed section 80, over a sprocket 86 on a nut 85 engaging a rotatable screw 83, and around sprockets 88, 89 on the moving section 81 to the lifting carriage. The switch 40 of the previous embodiment is mounted on a nut on a screw driven from the screw 83 and is associated with a cam cylinder provided with projections corresponding to the indentations 39. The preselector switch 42 is omitted, the arrangement being that the " lift " switch is closed until the lifting carriage has passed the predetermined height immediately prior to the selected height. The " lift " switch is then opened and the carriage continues to rise until the switch 40 is actuated by the selected projection on the cam cylinder, thereby stopping the motor.