UNDERGROUND CONSTRUCTION
LIFTERS, MANHOLE, COVER

Manhole Covers can be notorious to remove. Either stuck in place by silt and mud or too heavy to lift without damaging your back.

The GPO tried a number of lifters and some are mentioned here.

Taken from
The Post Office Electrical Engineer's Journal
Volume 51, Part 1 - Dated April 1958

Manhole Cover Lifters

The covers fitted to carriageway jointing chambers are necessarily heavy since they are designed to with stand any load that may be applied to them by modern road traffic, and consequently they often present difficulty to the staff who have to lift and move them in order to enter jointing chambers. In the past a number of improvised methods have been adopted to ease the task, but more recently, after discussion with representatives of the Staff Associations, it was decided to explore the possibility of producing a wheeled device for lifting and removing these covers.

A cover-lifting device based on a pair of 6-ton hydraulic jacks, and known as Manhole-Cover Lifter No. 1, is already in use for removing tight covers, and first efforts were directed to making this equipment mobile, so that after a cover had been lifted it could be wheeled away. No suitable method could be devised, however, without rendering the equipment so heavy and cumbersome that it would be unlikely to be used.

The second form of cover lifter considered was one developed. by a manufacturer, consisting of a collapsible tripod surmounted by a hydraulic jack. The T-section legs are fitted with castor-type wheels, and the lift is effected via hooks and chains connected to each end of a short bar on the top of the hydraulic jack. The original design, in which the Jack was mounted on a platform on top of the tripod, was unsatisfactory as it was found to be unstable under load. The makers were asked to lower the jack so that it was within the tripod, the side thrust from the legs being taken on a steel sleeve surrounding the jack body. This was done, and proved satisfactory. The equipment is designed to work at a maximum load of 3 tons; if this figure is exceeded the yield point of the chain material is exceeded and permanent deformation results.

A third equipment, also developed by a manufacturer, was brought to notice by the Regional Director's Office, South Western Region, and, consists essentially of a lever, the fulcrum of which is the axle of a pair of wheels.

The cover-lifting keys are suspended from a square section cross-bar, fixed to the end of a flat steel strip which is suitably angled at its other end to accommodate a tubular steel handle. The flat strip fits into slots at the top of a V-shaped member which is welded to the axle.

The strip is secured in place by chained pins through suitably drilled holes, and three pairs of holes are provided in the strip to allow adjustment for different cover sizes. The tubular handle is also secured to the strip by a chained pin. The axle is made from angle iron, reinforced by a length of steel rod welded in the angle. Two sets of keys are provided, one for manhole covers and the other for joint-box covers. The pins at the end of the cross-bar are to prevent the keys and cover from slipping off the bar. The equipment may be easily and quickly dismantled into four main parts by removing three pins.

Comparative trials were carried out with the tripod and lever devices, from which it was concluded that the latter was the more suitable for Post Office use. The tripod needs greater care in setting up, is slower in operation and is more difficult to wheel away when the cover is suspended from it. There is also the danger of one leg slipping into the jointing chamber, although this may be overcome by running the castors in suitable lengths of channel iron placed alongside the opening. It is proposed to introduce the lever device, under the title of Manhole-Cover Lifter No. 2, for under ground gangs and jointers whose work entails the frequent lifting of heavy covers. The device is not intended to lift very tight or jammed covers, which should be dealt with by the jacking device mentioned earlier (Manhole-Cover Lifter No. 1).