Anti Working at Height Remote Release Lifting Clamp / Hook
Remote release hook for the lifting, positioning and releasing a load without the need for a person to climb on to a load to release the hook
Compliance With The Working at Height Regulations 2005 - The Work at Height Regulations 2005 state: "There is a simple hierarchy for managing and selecting equipment for work at height. Duty holders must avoid work at height where they can"
Traditionally a crane driver, his rigger or an assistant will need to climb on a vehicle and / or the load to release the slings; an action that may need to be repeated many times with each delivery or during a working day. Our safety hook makes it possible to release the slings from the load without the need to work at height which in turn means that the user does not need a fall arrest or rescue plan. It may be argued that with some cargo's the safety hook may not totally elevate working at height with vehicle cranes though that we will all agree that a 50% reduction in working at height means there is only a 50% change of a fall occurring! The first rule for working at height is to avoid doing when ever possible!
Vehicle crane applications
We at SELS are now developing a new version of our remote release hook system for retro fitting to vehicle cranes commonly known as Hi-ab cranes. The hooks will be available in capacities to suit our customers requirements and with radio remote control removing the need for the manual pull chains which may be obstructed by the load. We can supply the hooks with a top suspension eye or fully integrated in to the Hi-ab's own hook, becoming a permanent fitting of the crane.
|Manual Release Safety Hook fitted to the Hook on an IHAB||Manual Release Hook fitted to a HIAB|
The hook is designed with a double safety mechanism that locks the load hook in position preventing the load from accidentally being released - even if the user accidentally pulls on the release rope or if the release rope gets snagged! All the weight of the load must be taken off the hook before the release mechanism will activate. First the pull chain on the left is pulled to release the first safety pin then the right chain is pulled rotating the internal cam and opening the hook.
What makes this hook unique is that it can be used for many applications allowing the hook to be released from the load without the need for the rigger / crane operator to climb on to the load / lorry trailer and therefore not exposing them to a potential fall. The clamp uses a wire rope looped around the truss / load lifted in a suitable position to lift and hold the load in-situ. When the lifting arrangement requires disconnection from the truss this can safely be accomplished from ground level or from a point of safety by the use of twin ropes/chains. (please see ‘How clamps work’ section for a detail explanation).
This clamp / hook was originally designed for lifting and positioning roof trusses on the back of a vehicle; it was designed because the rigger could not reach the crane hook to manually release the load. It is generally accepted that persons should not work at height unless absolutely necessary; with this unique hook users have the ability to release the hook from the load (from floor level) with-out the need to work at height - thus no requirement for a fall arrest or rescue plan and persons can safety work alone!
How The Clamps Work
This type of clamp uses two ropes / chains to control the position of a cam and latch mechanism. One end of a wire rope is firmly fixed to a hook on the side of the clamp. The free end is looped under the top member of the truss/load in a suitable position and then fitted into the mouth of the clamp. The moving hook of the clamp is then entered into the eye of the rope and the clamp locked.
Fig 1. General Layout Front View.
Fig 2. shows the clamp in the locked position lifting a load. The weight of the load forces the hook follower into a grove on the cam effectively locking the cam in position. When the weight of the load is removed a small spring unlatches the follower from the grove, rope A is now free to move. See fig 3.
Pulling rope A rotates the cam clockwise 90° releasing the locking latch / safety flag. See fig 4., the safety flag protrudes from the clamp indicating that the clamp is in an unlocked position and is about to release the rope.
Pulling rope B now rotates the cam 180° bringing the cam cutout under the hook follower allowing the moving hook to open releasing the end of the lifting rope. The clamp then remains in this position ready for the next lift.
Fig 2. Locked lifting load
Fig 3. Locked without weight
Fig 4. Clamp primed for release
Fig 5. Clamp about to release
Fig 6. Release of wire rope
More Robust Remote Release Clamp