GB1144664A - - Google Patents

Abstract

1,144,664. Indicating system for length of cable wound in or payed out. SMITHS INDUSTRIES Ltd. 11 Aug., 1966 [27 Aug., 1965], No. 36984/65. Heading B8B. A system for indicating the length of anchor chain 10 payed out or wound in by a cable lifter 11, comprises a rotary visual indicator 19, a stepping motor 17 coupled to the indicator through a variable ratio transmission 18 and a pair of magnetically operable switches 15 and 16 connected to control the rotation of the stepping motor in dependence upon the rotation of the cable lifter 11 which has a magnet 12, 13 attached thereto. The variable ratio transmission 18 comprises a pre-tensioned, constant force spring whose ends are connected to and wound about a shaft of a reduction gear driven by the stepping motor and a shaft to which the pointer of the indicator 19 is secured. The amount of the pre-tensioned spring wound on each of the said shafts is adjustable to vary the drive ratio therebetween in dependence upon the diameter of the lifter 11. A second pre-tensioned constant force spring couples the pointer shaft to a fixed pin to prevent any backlash in the shaft. A repeater 20 comprising a further stepping motor, variable ratio transmission and indicator may be connected to the switches 15, 16.