Overhead Bridge Cranes

A bridge crane runs on an elevated runway system along the length of a factory, and provides three axis of hook motion (X, Y, and Z). The hoist moves the load up and down, the trolley moves the load right and left, and the bridge of the crane moves the load forward and backward. Both single and double girder overhead traveling bridge crane designs allow precise hook positioning and gentle load placement. Double girder cranes typically provide better hook height and are typically used on heavier duty cycle applications. Single girder cranes offer lower costs and can be designed for heavier applications.

Advantages of a Bridge Crane

  • Greatest flexibility for hook coverage and control over the load
  • Fewest number of physical obstructions on your factory floor

Top Running Overhead Bridge Cranes

An ASCE rail or square bar is installed on top of the runway beams. The wheels ride on the rail rather than directly on the runway beam.

Underhung Overhead Bridge Cranes

The end trucks of the underhung bridge crane ride on the bottom flange of the runway beam. Typically, an underhung runway is suspended from the roof of the building and is available only on lighter capacities, usually 10 tons or less.

Class D: Material Handling Systems produces Class "D" heavy duty bridge cranes as well as Class "C" moderate duty cranes. Class D cranes are made for heavier duty cycles and require less maintenance. They are designed to make twice as many lifts in an hour and lift the full rated load 30% more often than a moderate duty Class "C" crane.

Motors: On the bridge and the trolley are 60-minute motors. A Class "C" crane uses 30 minute motors. All motors have Class "F" insulation, which allows the motor to run hot and still work well. Competitors' cranes often have Class "B" insulation, which would cause the motor to burn out at temperatures that our Class "F" motors can withstand easily.

Single Girder vs. Double Girder

Single Girder

  • Single Girder Cranes are typically the most economical choice for light to medium duty bridge cranes.
  • They are available up to 100' span at 10 ton capacity, up to 80' at 15 ton, up to 60' at 20 ton.
  • Single girder cranes are available as both top running or under running. The crane runway beams hang from the existing facility overhead structure.
  • The advantages of single girder cranes (as compared to double girder) include economy and slightly lower loads delivered into the building or foundations.
  • The crane's main girder is above the hoist, therefore reducing the available hook height in a given facility.
  • The hoist trolley wheels ride on the relatively soft steel of the main girder bottom flange, therefore, the life expectancy of the structural beam is limited.
  • The trolley mechanical components are often less durable when compared to double girder top running trolleys.
  • Special features are often difficult to incorporate into single girder cranes i.e. service walks, lights, fast speeds, heavy service components, etc.
  • Light weight = lower wheel loads (less building steel)
  • Low head room monorail hoist
  • Lower production costs
  • Ease of maintenance
  • Ease of installation

Double Girder

  • Double Girder Cranes are typically used when the limitations of single girder cranes are reached.
  • Double Girder cranes are available up to almost limitless span and capacity.

The advantages of double girder cranes (as compared to single girder) include:
  • Traditionally are more durable than single girder
  • Excellent hook height relative to facility overhead obstructions
  • Wide range of special features available: much higher speeds, maintenance, serviceability and durability options, and special controls
  • If crane hook is the primary factor for the height of a new building, consider going with a double girdle crane. A much better hook height is achieved with a double girdle design. A small increase in crane cost can be much less expensive than the cost of a taller building, depending on the height of the building.

The disadvantages of double girder cranes (as compared to single girder) include:
  • Higher initial cost

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