GB1268352A - Improvements in or relating to lifting devices - Google Patents

Abstract

1,268,352. Lifting devices for manhole covers. POST OFFICE. 31 March, 1969 [1 July, 1968], No. 31281/68. Headings B8H and B8J. A lifting device for a manhole cover, comprises a lifting beam 1 of square section with a pair of fixed radius arms 2 carrying wheels 3. A further pair of radius arms 4 is fixed to the beam 1, a piston-rod 5 being pivotally secured thereto by a pin 6. The rod 5 is part of an hydraulic jack with a cylinder 7 having an enlarged reservoir portion 8 with a pump piston whose rod 9 is pivoted to a handle 10 itself pivoted to a lug 11 on the reservoir portion 8. A clamp 13 is slidable on the cylinder 7 and has projections 13a pivotally mounting a frame 14 consisting of rods 15 attached to a housing 16 and pivoted by pins 22 to further radius arms 22a on the beam 1. A castor wheel 20 is attached to the housing 16. Slidably mounted on the beam 1 are two sleeves 25 carrying hooks 26. Prior to use, the jack is fully retracted, Fig. 3: chain dotted lines, with the clamp 13 locked adjacent the portion 8. Lifting keys are then inserted in the manhole cover, the apparatus manoeuvred over the cover and the hooks 26, slid to suitable positions, engaged with the keys, clamp 13 being adjusted if necessary. The handle 10 is then operated to extend the jack. The beam 1 is rotated thereby about its longitudinal axis to move vertically, lifting the cover and taking up the full-line position shown in Fig. 3.