ESSENTIAL PARAMETERS FOR SPECIFING EOT CRANES - Part 2

Hello Structural Engineering readers, how are u? Today we continued some more tips about the above topic for your further explanation.

Other than addressing the last post (see here) parameters, some specific conditions applicable to your application must be mentioned.

1) Do you need the use of a second hoist on the bridge crane? (This hoist may be used as an auxiliary hoist or be required in a process such as tilting/tipping. In case you are handling long materials, like steel tubes and plates, the best solution are to have a crane with two hoists (and hooks) for better stability of the load ensuring safe lifting).

2) What will the operating environment be (dust, paint fumes, outdoor, etc.)?

3) Is there existing cranes on the runway? Then, consider the use of a collision avoidance or collision warning system.

4) Do you require a catwalk on the crane for maintenance access?

5) What other accessories are required such as lights, warning horns, weigh scales, limit switches, etc.

Load is defined as the maximum working load suspended under the load hook. Load block and ropes are not included in the rated load.

The design load for the crane system is based on the rated capacity plus 15% for the weight of the hoist and trolley (capacity x 1.15) and an additional 25% for impact (capacity x 1.25) for a total design capacity x 1.4. (Note 25% impact factor is good for hoists speeds up to 50 fpm).

The capacity of crane is the maximum rated load (in tons) which a crane is designed to carry. The net
load includes the weight of possible load attachment. For example , a 1000 lb crane allow you to pick up a 1000lb load, provided the hoist weighs 150lbs or less and the hoist speed is less than 50 feet per minute.

Under no conditions should the crane be loaded beyond its rated capacity.

Note that the Crane test loads are typically specified at 125% of rated capacity by both OSHA and ASME.