It’s more than simply employing equipment to operate a construction hoist. If you don’t have the ideal rig for the task, you’re losing out on considerable earnings potential. And if you’re seeing a recurring pattern in your fleet of down-renting with certain cranes, you’re wasting money.
Factors to Consider When Choosing the Right Construction Hoist for the Job
Here are the things you need to consider when recommending or choosing the right hoist for the job:
Determining Needed Construction Hoist Load Capacity
When purchasing a manual hand chain hoist, the rated construction hoist load capacity should be at least as great as the weight of the heaviest load to be lifted and no greater than the pad eye, monorail system, or other overhead structure from which the hoist will be suspended.
When determining the capacity required for an electric or pneumatic hoist, we must take into account not only the weight of the heaviest load to be raised but also the Mean Effective Load (MEL) and a MEL ratio of.65.
You can refer to ASME HST-1, Performance Standard for Electric Chain Hoists, Section 1-1.1 through Section 1-2.4.2 for more details.
Determining the Suspension Type
Chain hoists can be suspended from a hook or lug on the top of a trolley, or they may be dragged along by means of a forklift. Trolleys may be rigid or articulated, and their movement can be either hand-powered or motor-driven.
Understanding the Needed Lift, Reach, and Headroom
It’s logical to combine these three variables since they are all linked. Simply stated, the distance the load hook can travel between its fully lowered and fully raised positions is known as lift length.
The reach is the difference in elevation between the hoist suspension point (pad eye or trolley beam running surface) and the hook saddle when it is in its lowest position.
The headroom is the distance between the hoist suspension point and the hook saddle that is fully raised. The headroom of a hoist with top-hook suspension is measured from the top hook’s saddle to the bottom hook’s saddle.
Understanding the Operation Type
A hoist’s operation mode is defined by the energy source used to drive the lifting motion. Manual, electrical, or pneumatic (air) power are examples of operation types. Initial cost, access to electricity, duty cycle, lifting speed requirement, operating environment, and other factors must all be considered while selecting which one is ideal for a given application.
Understanding the Required Duty Class
The American Society of Engineers (ASME) and the Hoist Manufacturer’s Institute (HMI) have created and published standards for hoists, including duty ratings.
The hoist’s duty classifications are determined by a variety of criteria, including the number of lifts performed per hour during a given working period, the average and maximum load lifted, the frequency with which the maximum load is lifted, the distance that the load is raised and lowered on a regular basis, and how many stops and starts occur per hour.
Choosing the Lifting Speed
The speed at which a hoist raises or lowers a load varies considerably, and it is important to think carefully before making a selection. For long lifts or shorter lift applications in which a large number of lifting/lowering cycles are required over a short period of time, faster hoist lifting speeds are preferred.
The amount of weight to be lifted, as well as the required lifting speed and hoist gear ratio, determine the torque demand, which in turn dictates the motor horsepower needed to supply that torque. Higher horsepower motors may increase the size, weight, and cost of a hoist while lowering its performance. Keep in mind that the speed of the hoists depends on the weight of the materials to be lifted, i.e., the lifting capacity.
Determining Dimensional Constraints
Consider any dimensional restrictions that may apply in the region where the hoist will be used when selecting a hoist. End approach clearances, for example, are particularly important dimensions.
The distance between the centerline of the lifting hook and the end of a monorail beam, bridge beam, or runway on which the hoist is operating can be defined as an “end approach” (see dimension “A” to the right).
Determining the Needs for Specific Environments
The normal chain hoists are made for “common usage.” Hoists with special modifications or optional features that are built for particular conditions such as extreme temperatures, exposed outdoor areas, salt-water marine environments, corrosive atmospheres, classified hazardous areas, clean rooms, and wash-down locations could be required.