How to Buy a Gantry Crane

There is a lot of specialized terminology when it comes to gantry cranes. We have defined the terms you will need to know in order to be able to narrow down your options.

• Capacity
  The amount of weight the crane is designed to carry.
• Caster Diameter
  Outside Diameter (OD) of the caster (ranges from 6” to 12” depending on load rating).
• Caster Frame Spread
  The size of the “base” on the crane.
• Clear Span
  Distance between brace legs (if present).
• I-Beam Depth
  Height of the I-Beam, ranges between 4” and 24”, dependent on Span and Capacity.
• I-Beam Span
  Overall Length of the I-beam. While most charts show 5-foot increments, I-beams can be cut to fit.
• Leg Clearance
  Distance between the legs at the bottom of the I-beam. This tells you if a hoist can fit through the legs.
• Overall Height
  Height of the crane from the floor to the highest point.

While not a complete list, knowledge of these basic parameters will help you find a crane to fit your particular needs.

Next is an overview of the different models Wallace has to offer.

Wallace gantry cranes come in six different models. The difference between models has to do with:

• the material they are made of e.g. steel, aluminum, or a hybrid (steel frame with aluminum i-beam mix);
• whether the crane is fixed or has an adjustable height, span, tread, and/or caster frame spread; and
• the crane’s lifting capacity, span, and height.

A brief description of each of the models is provided below. While Wallace can easily modify many of the “standard” models, some parameters cannot be changed. For example, the span and the desired load lock in a given I-beam section. And while caster frames can be “adjusted”, the amount of adjustment is limited by the requirement to keep the crane stable both statically and while rolling.

Tri-Adjustable

• Steel, Aluminum, or Hybrid
• Adjustable Height
• 1/2 to 10 Ton Capacity
• Spans from 10 to 35 Feet
• Heights from 4′ 2″ to 24′ 0″

Thrifty

• Steel or Aluminum
• Fixed or Adjustable Height
• 1/2 to 7 1/2 Ton Capacity
• Spans up to 35 feet (lower heights and shorter spans in Aluminum)
• Heights from 6′ 7″ to 18′ 4″

Hippolift

• Steel
• Fixed Height
• 1 to 5 Ton Capacity
• Spans 10 to 35 Feet
• Heights: Nominal 10, 13 or 16 Feet

Mighty-Mite

• Steel
• Fixed Height
• 500 to 1000 Pound Capacity
• Spans from 8 to 15 Feet
• Heights from 5′ 3″ to 12′ 0″

Made-to-Order

• Steel
• Fixed Height
• 15 Ton Capacity
• Heights from 15′ 1″ to 23′ 10″
• Spans from 15 to 35 feet

Custom

• Wallace will customize any crane
  to fit your needs
• Fixed and Adjustable Height
• 1/4 to 15 Ton Capacity
• Spans 8 (or less) to 35 Feet
• Heights: 4’2″ (or less) to 23’10”

The weight of the load you want to lift will determine the maximum lifting capacity of the crane models you can choose from. Wallace has gantry models with capacities ranging from one-quarter to 15 tons.

Bear in mind whether the load will have to be lifted over equipment on the shop floor or whether there are any overhead obstructions or ceiling restrictions as this will also reduce the amount of space you have available to lift a load. The crane itself has parts and pieces that will have to be factored into your calculations.

Stacking

Stacking is an important consideration when deciding how high you have to lift the load. Stacking includes everything underneath the I-beam that effectively reduces its lifting height potential. Stacking includes the space needed for the trolley, sling usage, and hoist.

Trolley

Spreader or I-Beam

Manual (Trolley) Hoist

Electronic Hoist

It is imperative to understand that a hoist must be suspended with a hoist/trolley combination or at least a beam clamp. You should never attach a hoist to the I-beam with a sling. Slings are frequently used to pick up both bulk materials and delicate or oddly shaped objects. While convenient, slings can add substantially to the “headroom” and thereby reduce the amount of space you have available to lift a load.

Sling Usage

This image clearly shows that sling height is close to the headroom of most hoists, so make sure you are factoring that in when you are deciding on the height of your crane.

Headroom Basics

• Hoist Headroom
  Hook to Hook Distances
• Hook Height
  Distance from the wheel surface of the gantry crane (i.e., the floor) to the fully raised hook of the hoist. Subtract this distance from the Overall Crane Height to see if a given crane will “fit.”
• I-Beam Depth
  For a given capacity and span, this number cannot be changed.
• Trolley Headroom
  Distance from the bottom of the I-beam to the top of the hook.

The sketch above shows a “typical” trolley and hoist mounted on a 12” I-beam. As stated before, when you start to consider all the heights for the crane brackets, trolley hook height, I-beam depth, hoist “hook-to-hook,” the amount of available space “below” the hook decreases rapidly. Wallace sales staff are happy to help you choose the correct crane and hoist/trolley combination to meet your lifting requirements.

Before buying, make sure the location is suitable for the crane.

Wallace Cranes are designed to move on smooth flat, concrete surfaces. While the proprietary four-bar linkage ensures the casters are all on the floor, you should avoid moving the crane over obstructions and debris.

There are a few cautions to be noted about the concrete flooring. Because of the loading of the crane transmitted to the floor through the casters (essentially a “line load”), the flooring beneath a crane should be 3,000 psi (pound-force per square inch) concrete at least 18” deep with one or more courses of rebar. The standard Wallace casters, in either phenolic or steel core with polyurethane tread, are fully capable of smoothly running the crane across the floor at full load.

An option is to have the crane track mounted. For these cranes, typically with an electric motor drive, the casters are replaced with V-groove steel, running on a track (angle iron mounted on a plate). Wallace builds this track in-house with three different capacities, 1-5 tons, 8-10 tons, and 15 tons. The track sections are available in standard 5 and 10-ft lengths, with male and female sections for smooth running. The track is held in place with a Wallace Track Clip (a cast iron part) bolted to the high-strength concrete floor. Wallace also makes track with end stops and a removable transition section for high traffic areas.

Will the hoist and trolley be manual or electric? If the hoist is electric, what is the required voltage? Higher capacity hoists, greater than 3 tons, generally require 3-phase electricity.

Links to information on National standards are below.

Call or contact us if you have questions or would like additional information about any of our products and services. We would be more than happy to assist you.

• American National Standard Institute (ANSI)
  http://ansi.org/
• American Society of Mechanical Engineers (ASME)
  https://www.asme.org/
• Occupational Safety & Health Administration (OSHA)
  https://www.osha.gov/.