Overhead Cranes

Bumpers

Bumpers are designed to absorb the crane's energy and reduce impact—bringing the crane to rest in a controlled manner and minimizing forces when the crane or trolley reaches the end of its travel. Bumpers can be attached to the bridge, trolley, or runway stop.

Controls

Controls are typically mounted in a panel on the crane or hoist and the pendant or remote console allows the operator to run the crane. The controls operate the drive and hoist motors, and can control Variable Frequency Drives (VFDs) to control hoist speed for precise load positioning.

Workstation crane features

- Capacities from 150 to 4,000 lbs. - Rectangular Coverage with up to 34' bridge and 124' runway standard - Standard support distances of 20, 25 and 30 feet - Custom support distances are available - Easy to move and position loads - Modular design for greater flexibility - Doesn't require existing support structure

Runway rail or tracks

Rail supported by the runway on which the crane travels. Top-running cranes typically run on ASCE/railroad rails. Gantry cranes can also utilize a rail or track system installed on the floor to move the bridge back and forth.

Hoist

The hoist is what makes the lift and holds, raises, or lowers the load using wire rope or chain. Hoists can be powered manually (by hand), with electricity, or with compressed air (pneumatic).

Hook

The lifted load is supported using a hook which connects to the hoist.

Trolley

The trolley supports the hoist and moves horizontally along the crane's bridge, to position the hoist and hook, prior to picking up or lowering a load. Trolleys can be configured in an Under Running or Top Running design.

Double Girder

There are two girder beams that make up the bridge and they are supported by an end truck on each side. The trolley and hoist run on a rail installed above or below the bridge girders. Double girder cranes are recommended for heavier-duty applications where the crane has to handle heavier capacities and longer spans

Class A (Standby or infrequent service)

This service class covers cranes where precise handling of equipment at slow speeds with long idle periods between lifts are required. Capacity loads may be handled for the initial installation of equipment and for infrequent maintenance EX) Cranes used in powerhouses, public utilities, turbine rooms, motor rooms, and transformer stations. This is the lightest crane as far as the duty cycle is concerned.

Class C (Moderate Service)

This service class covers cranes where service requirements are deemed moderate, handling loads which average 50 percent of the rated capacity with 5 to 10 lifts per hour, averaging 15 feet, with not over 50 percent of the lifts at rated capacity. EX) cranes used in machine shops, paper mill machine rooms, etc.

Class B (Light Service)

This service class covers cranes where service requirements are light and the speed is slow. Loads may vary from no load to occasional full-rated loads with 2 to 5 lifts per hour, averaging 10 feet per lift. EX) Cranes in repair shops, light assembly operations, service buildings, light warehousing, etc.

Under running cranes are often called "underhung," because the crane wheels are supported by the bottom flange of the crane runway beams acting as the crane rail.

True

Single Girder Top Running

Typical Load Capacity: .25 - 20 tons Typical Span: Under 65 feet Typical Service: Light Low deadweight More overhead space High speed Lower production cost / lower overall price

Double Girder Top Running

Typical Load Capacity: 20-400 tons Typical Span: Over 65 feet Typical Service: Heavy Ideal when extremely high hook height is necessary Better hook height Most overhead space More lift High speed

Workstation crane

Workstation cranes are designed to allow the operators an ergonomic means of moving or lifting loads with limited effort in a smaller size work area. Workstation cranes are typically lighter-duty systems—lifting materials from 150 lbs. up to 2 tons in capacity. They're designed for repetitive lifting of loads, the positioning of loads, increasing worker productivity and ease of work flow.

Class D (Heavy Service)

In this type of service, loads approaching 50 percent of the rated capacity will be handled constantly during the work period. High speeds are desirable for this type of service with 10 to 20 lifts per hour averaging 15 feet, with not over 65 percent of the lifts at rated capacity. EX) Cranes used in heavy machine shops, foundries, fabricating plants, steel warehouses, container yards, lumber mills, etc., and standard duty bucket and magnet operations where heavy-duty production is required.

Class F (Continuous Severe Service)

In this type of service, the crane must be capable of handling loads, approaching rated capacity continuously under severe service conditions throughout its life. EX) Custom-designed specialty cranes essential to performing the critical work tasks affecting the total production facility, providing the highest reliability with special attention to ease of maintenance features.

Steps to purchasing a crane

- First contact with the overhead crane manufacturer - Consultation

What are popular reasons to use an overhead crane?

- Loading or unloading materials from a truck - Moving materials around a facility more effectively than a tow motor or man power can - Flipping or pulling dies in and out of stamping machines at a manufacturing facility - Feeding raw material into a machine at a manufacturing facility - Moving pieces or parts down an assembly line in a controlled fashion - Moving containers around a shipyard or railyard

What is a Monorail Crane?

- Most commonly found in a production or assembly line, this type of crane uses a trolley to carry the hoist along a single path. Monorail cranes do not utilize a bridge or girder design—instead, the trolley is designed to connect to an I-beam, often already built into the ceiling structure, and runs along the flat surface (flange) on the bottom of the beam. They can also utilize a configured support structure as well. - Material can be run back and forth in a straight line, or the rails can be designed with curves, branches, switches, and with changes in elevation. Monorail cranes follow a singular path and are designed for lifts that do not require the side-to-side trolley movement provided by the bridge in an overhead or gantry style crane.

What are the benefits of an overhead crane system?

- Reduction in workplace accidents - Reduction of material or property damage - Improved workflow - Lowered costs - Green solution that reduces environmental impact - Cuts down of repetitive motion injuries and muscle strains - Can work up to 2-3 times faster than using workers or tow motors

Under Running Cranes

- Typically designed for lighter service / lower capacity applications - It can become impractical and expensive to engineer an under running crane to make it a high-capacity piece of equipment - Offers excellent side approaches and maximize utilization of the building's width and height when supported by roof or ceiling structures - Hook height is less than top running because bridge and hoist hang underneath runways

gantry crane

A gantry crane is similar to a bridge crane, but instead of moving on suspended runways, the crane uses legs to support the bridge, trolley, and hoist. These legs travel on rails that are embedded in, or on top of the floor or ground structure. A gantry crane is ideal when you require a lightweight and quick knockdown crane for applications that require portability and corrosion resistance. They are also considered when there is a reason not to incorporate an overhead runway system and are most traditionally used in outdoor applications where full beams and columns can't be installed, or they can be used below an existing bridge crane system. Gantry cranes are commonly found in shipyards, railyards, special construction sites like where a bridge is being built, or in places like steel mills where overhead room may be an issue

Bridge

A load-bearing beam that runs the width of the building. This is the primary structural component that connects the runways and moves the hoist forward and backward using a trolley. A bridge can be comprised of one or two beams—more often referred to as a single girder or double girder design. Girders can be made of rolled steel or can be fabricated by welding the beams into a steel box design.

Electrification

Insulated conductor bars, festoon systems (flat cables), or cable heels bring power to the crane from the building.

End trucks

Located on either side of the bridge, the end trucks move the bridge up and down the runway utilizing a series of wheels that ride on the rail. Each end truck can have a configuration of 2, 4, or 8 wheels based on the crane's capacity

Single Girder

The bridge consists of one girder beam supported on each side by an end truck. The trolley and hoist are underhung— meaning they run on the bottom flange of the single girder. Single girder cranes are typically less expensive due to... - Reduction in freight expenses - Faster installation - Simpler hoist and trolley design - Lighter runway beams

Class E (Severe Service)

This type of service requires a crane capable of handling loads approaching the rated capacity throughout its life with 20 or more lifts per hour at or near the rated capacity. EX) Magnet, bucket, magnet/bucket combination cranes for scrap yards, cement mills, lumber mills, fertilizer plants, container handling, etc.

Jib crane

Used for lifting materials; Attached to floor or wall of warehouse; a load-bearing beam and hoist from its mast; Can pivot as much as 330 degrees; useful at workstations or machining centers

Runway

What the bridge crane travels on to move the crane up and down the bays. These are typically part of the building structure, as beams, and there are two (2) per overhead bridge crane system.