Choosing The Right Chain Hoist

Plant engineers and maintenance personnel understand that hoists play an ongoing vital role in the manufacturing environment. Hoists lift materials and move finished products, while taking abuse in the process.

03/01/1998


Plant engineers and maintenance personnel understand that hoists play an ongoing vital role in the manufacturing environment. Hoists lift materials and move finished products, while taking abuse in the process.

Carefully selecting and installing the hoist to match the job saves time and money and goes a long way toward maximizing operating efficiency and extending service life. (Although this article was prepared for chain hoist selection and installation, most of the information is equally appropriate for wire rope models.)

Getting started

Planning is the crucial factor in a successful hoist application. This process helps identify requirements and available resources. Obtain input from a variety of sources -- engineers, maintenance staff, operators, distributors, and manufacturers -- before making the selection.

Application should be clearly defined. Will the hoist be used solely to lift materials and equipment, or will it lift and move these items? The answer dictates the type of hoist needed.

Capacity is obviously important. How much weight will the hoist lift and/or move? Other factors include the height of the lift, height of the hook point (where the hoist will be mounted), and type of operator interfaces, such as hand chains or push-button pendants.

Frequency of use is critical. If lifting and moving loads frequently, an electric chain hoist is the best choice. If the hoist will only be used occasionally, a hand chain hoist should suffice.

If a trolley is required for horizontal motion, the type installed should correlate with the frequency of use. A plain or geared trolley requires the operator to start and stop the movement of the load by hand. Manual trolleys are usually satisfactory for occasional lifts and intermediate loads. A motorized trolley is ideal for frequent, heavy loads.

Electrical requirements

Determine available voltage and whether it is single or three phase. Industrial three-phase power is the preferred choice, because it is more efficient and there is more equipment from which to choose. Single-phase hoists should only be considered if three-phase power is not available.

If the application requires a trolley, give thought to getting power to the hoist. The most common approach is a festoon system consisting of a flexible power cord attached to rollers. Rigid conductors and collectors are another popular way to conduct power to the hoist.

Regardless of the electrical requirements, the hoisting system needs a power disconnect and overcurrent protection. These and other requirements are specified by the National Fire Protection Association, National Electrical Code, and OSHA.

Measure headroom

Another important preinstallation factor is headroom, which is the minimum distance between the two hook points. Determine the height of the hoist's bottom hook, as well as the height of the upper hook point. Make sure the hoist meets headroom requirements. Typically, lug-mounted hoists have less headroom (C) than hook-mounted models

Compare the distance between those heights with advertised headroom values from the hoist manufacturer. If required headroom is less than what is available as standard, change the hook point or obtain a hoist specially designed with a lower headroom.

Final planning

Work closely with an experienced electrical contractor, construction firm, and distributor to define requirements and select the proper components. Be sure that the building structure meets hoist system requirements.

Make sure all hoist operators read the operating and maintenance instructions provided by the manufacturer before using the equipment. Complete and return warranty certificates to the manufacturer. File the parts list and maintenance instructions for future reference.

Installation procedures

Allow ample time to complete the installation. Remember that the operator needs good solid footing and plenty of room to maneuver the hoist without interfering with normal traffic flow. Make sure the power source is turned off and properly locked out before beginning the installation.

Ensure the structure will support the hoist, as well as the hook or lug. If the hoist will be used with a trolley, install the trolley stops at each end of the beam. Then follow the manufacturer's instructions for hanging the trolley, which should be properly adjusted to the beam size. Once the trolley is secured, hang the hoist to it.

Next, begin a series of checks and tests. For example, the top hook should be seated properly in the hook point, and the hook latch should be closed. Check all clearances for the hoist, trolley, and crane system (if necessary) to ensure there is unobstructed movement. Make sure all nuts, bolts, and pins are secured in the hoist/trolley system.

Electrical connections should be secured, circuit protection in place, hoist and building voltage matched, wires sized according to code, and line phase matched to the hoist.

If the hoist is manual, move the chains and trolley -- with no load -- to ensure they travel freely.

Activate the power to check for proper operation. With no load on the hoist, run it and the trolley through their full range of motion. Make sure the travel limit switches work properly. Test the hoisting system with about 10% of rated capacity, and watch and listen for anything unusual. If the hoist passes this test, operate the unit with a full load.

If the hoist passes both tests, do one final check of the entire system. As a precaution, reread the manufacturer-supplied instructions and double check that all operators have the proper training and education to run the hoist.

Inspection and maintenance

Regular inspection and maintenance programs keep the hoist running efficiently and productively. They help ensure that the hoist is in proper working order for many years to come.

Inspections include checks for external damage, loose parts, worn chain, stretched hooks, and lack of lubrication. Be sure to examine hoists after storage and transportation. If a hoist doesn't pass inspection, tag it "Out of Service" and remove it from the area for repair by a hoist specialist.

Maintenance extends hoist life. Establish a regular routine for qualified personnel to follow. Prescribed methods and appropriate materials are available in the hoist manufacturer's operating and maintenance manual, or by checking with organizations such as OSHA, ASME, and ANSI.

Different kinds of hoists require various maintenance levels and procedures. For example, a manual hoist contains bearings, bearing points, gears, and other parts that require regular maintenance. An electric hoist requires maintenance on push button switches, contactors, and cables.

The proper kind and amount of lubrication help reduce friction and wear, and prevent parts from rusting. Likewise, worn or failing components should be replaced with new parts, according to the manufacturer's specifications. Make sure replacement parts meet or exceed those specs. Also, protect the load chain from weld spatter or other damaging contaminants. Always keep maintenance records current.

--Edited by Ron Holzhauer, Managing Editor, 847-390-2668 r.holzhauer@cahners.com

More info

The author is willing to answer technical questions concerning this article. Mr. Olson can be reached at 800-233-3010. A previous article presented related material: "Comparing Powered Hoist Options" (PE, September 1996, p 78, File 4525/7040/5550).

Key concepts

Planning -- with particular attention to application, capacity, and use -- is the most important selection step.

Careful installation according to manufacturer guidelines, followed by regular inspection and maintenance, keep hoists performing at peak efficiency.

Crane considerations

Using a hoist with a crane system presents a unique set of considerations. There are several major factors to consider:

- Runway structure design and installation

- Additional equipment required to raise large, heavy components

- Crane clearances

- Additional controls and electrification

- Building load capability

- Anticipated future use of crane.

Inspection guidelines

How often?

Frequent inspection is visual examinations by the operator or other designated personnel with records not required.

- Normal service -- monthly

- Heavy service -- weekly to monthly

- Severe service -- daily to weekly

Periodic inspection is visual checks by a designated person who makes records of external conditions to provide the basis for a continuing evaluation. An external coded mark on the hoist is an acceptable identification in place of records.

- Normal service -- yearly

- Heavy service -- semiannually

- Severe service -- quarterly

What?

Frequent inspection

- Trace of slipping via braking

- Control functions for optimal operation

- Damage, cracks, and bends in hooks or noticeable openings

- Hook latch operation

- Optimal lubrication, signs of wear, link damage, or adhesion of foreign matter to the load chain

- Load sheave and idle sheave engagement with load chain; load chain twisting

Periodic inspection

- All items included in frequent inspection

- Fastening of screws, bolts, and nuts

- Wear, corrosion, cracks, distortion, etc. of the hook block, gears, bearing, and chain pins

- Damage to, or excessive wear of, the load sheave chain pocket

- Friction discs

- Sticking of contactor or contact point deterioration for electric hoists

- Valves and airlines for air-powered hoists

- Imperfect insulation of cables, cords, and control station

- Damage to supporting structures

Six keys to maintenance success

1 Keep detailed records of all inspection and maintenance activities, whether they are performed by the inhouse staff or a professional hoist inspection and repair company.

2 Know the hoists inside and out. Manual hoists contain bearings, bearing points, gears, and other parts that require regular maintenance. Electric-powered hoists also require maintenance on electrical parts such as fuses, push button switches, power contactors, and conductors.

3 Replace worn or failing components with new products, in accordance with the manufacturer's specifications. Keep in mind that different hoist models require different parts.

4 Use the proper type and amount of lubrication to help reduce friction and wear, and prevent parts from rusting. If maintaining an electric hoist, keep oil in the gearbox at the prescribed level and use the specified type of oil. Be sure to lubricate the chain, gears, hooks, guide rollers, brake, and limit switch. Gear oil should be changed at least annually. The chain should be lubricated at least weekly, depending on the severity of use. Lubricate the chain more frequently if you use the hoist in a corrosive environment. On trolleys, lubricate the handwheel shaft, side rollers, and suspender shaft.

5 Take proper precautions before performing maintenance. Make sure the hoist is unplugged from any electric power source, and lock open power circuits that cannot readily be unplugged. Allow only qualified personnel to perform maintenance. Attach a tag stating "Danger: Do Not Operate; Equipment Being Repaired" to the hoist. Never perform maintenance on a hoist supporting a load.

6 Follow prescribed methods and use appropriate maintenance materials. Also, consult the manufacturer's operating and maintenance manual or check publications of technical societies such as the ASME and ANSI

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