ELEVATORS AND CONVEYORS
An elevator usually moves materials from a higher point to a lower point, like in buildings. It is different from conveyor belts, which transport materials horizontally. Elevators are not very common in construction sites because they are expensive to use, but on a larger site where the concrete mixer is located at one end of the site, an elevator might be the best option because of its large capacity and ease of use. Conveyors can be used for most large construction sites, but only if the building has both small and large aggregates; otherwise it is too expensive.
Hoists are used to transport materials and passengers vertically by means of a moving level platform. These lifts are typically designed for specific uses, but newer models are oriented towards combined loads of materials and passengers. Passengers should not be transported on hoists that were only designed for lifting materials.
Generally speaking, there are two types of hoists: static and mobile.
In the static version, a tower is erected, with the lift platform attached on top. The hoisting mechanism can either be suspended from a small mast or mounted on either side of the tower. All items need to be solidly connected at the intervals prescribed by the manufacturer in order to ensure stability; these items will usually reach heights of 24 meters or higher. Mobile elevators usually have a maximum height of 24 meters and do not need to be securely fastened unless extensions are added to them, in which case they act as cantilever hoists. All mobile elevators should be positioned on firm ground and jacked up first to ensure stability. Operators of materials elevators should always follow this rule: always trust trained drivers who can position themselves for optimum safety from inside the operating compartment. Instructions for use should also always be clearly provided at all times for site personnel, such as instructing how loading requires placing wheelbarrows at ground level (with handles facing towards the top) before being raised by the mechanical platform. That way, ascending and descending from a raised height is minimized at all times.
To elevate materials or people, one can use a passenger or materials hoist. Passenger hoists can be powered by petrol, diesel, or electric motors and can either be of a cantilever or enclosed variety. The cantilever type consists of one or two passenger hoist cages that operate on one side of the cantilever tower; the alternative version consists of a passenger hoist cage operating inside an enclosing tower. Tying-back requirements are similar to those for the materials hoist. Passenger and material hoists should conform to BS 7212: Code of practice for safe use of construction hoists.
The Lifting Operations And Lifting Equipment Regulations 1998
The Health and Safety at Work Etc Act 1974 provides various regulations for assessing hoists’ risks. To summarize, the following regulations should be followed:
- Anywhere access can be gained, and anyplace someone at ground level might be hit by the platform or counterweight, enclosures and gates should be 2,000 meters high. Access gates must always stay closed unless it’s necessary to load or unload the platform. The platform itself should have a device that can support a full load in case the hoist ropes or gear fail. Likewise, the hoist should also have an automatic safety device to stop the platform or cage from overrunning.
- Hoisting operations must be done from one designated point at all times. If the operator can’t watch the hoist during operation, they should either use visibility devices or someone to communicate with. Furthermore, there should be someone or something between the operator and the object being lifted to make sure that these obstacles are never in the way of the moving hoist.
- Winches and carriers must have independent devices and an automatic braking system that is applied when the controls are not in the normal operating position. Multiple roping or cylinders (hydraulic hoists) should also be a standard facility for various equipment.
- Keep your eye out for a maximum weight limit. There should also be nosings, which are the part of the stairs where a step starts. Remember that right and left nosings can differ in terms of height.
- The examination and inspection of a hoist includes the input of trained, competent employees with the abilities to ensure that the hoist is safe to use.
- All machines should be given a pre-use inspection at the start of each day, after any changes to height or righting and before use. The machine’s measurements should have a thorough inspection every few days, or after any harsh work. Those results should be recorded in a log book and filed with the department head.
- Passenger-carrying hoists must have requirements like gates, over-run devices and other safety features that ensure passengers aren’t trapped. With these features, we can lower items without fear of the cages getting stuck, or are functioning incorrectly.
- It is necessary for facilities to be in place for prevention of movement or tipping of materials during transportation by hoist. Loads of material should be secured from movement by containers such as wheelbarrows that are blocked or otherwise restrained.