A double shoe collector is a device that is used to collect electrical power from a conductor bar in an overhead crane. It consists of two shoes that are mounted on a pivoting arm. The shoes are made of a conductive material, such as copper or aluminum, and they have spring-loaded contacts that make contact with the conductor bar.
The purpose of a double shoe collector is to provide redundancy in the event that one of the shoes loses contact with the conductor bar. This is important in cranes that use variable frequency drives(VFDs), as VFDs can cause the collector shoe to lose contact if there is a sudden change in load.
The CMAA (Crane Manufacturer's Association of America) specifications 70 and 74 require the use of a double shoe collector on all cranes that use VFDs. The specifications also state that the collector shoes must be made of a non-magnetic material, such as copper or aluminum.
Reasons why a collector shoe might lose contact with the conductor bar.
- Normal wear and tear
- Mismanagement of the crane
- Expansion of joints
- Stagnation of dirt in the collector shoe
To prevent collector shoe loss of contact, it is important to:
- Inspect the collector shoes regularly for wear and tear
- Properly manage the crane
- Inspect the joints for expansion
- Keep the collector shoes clean
If a collector shoe does lose contact with the conductor bar, the crane will shut down to protect the electronics. The crane can be restarted by resetting the VFD.
In addition to providing redundancy, a double shoe collector also helps to improve the efficiency of the crane. This is because the two shoes can share the load, which reduces the amount of heat that is generated.
Overall, a double shoe collector is an important safety feature that can help to prevent crane failures. If you are operating a crane that uses a VFD, it is important to make sure that it is equipped with a double shoe collector.
Additional benefits of using a double shoe collector:
- Increased reliability: A double shoe collector is less likely to lose contact with the conductor bar than a single shoe collector. This reduces the risk of crane shutdowns and other unplanned downtime.
- Improved safety: A double shoe collector helps to protect the crane's electronics from damage in the event of a collector shoe loss of contact.
- Increased efficiency: A double shoe collector can help to improve the efficiency of the crane by reducing the amount of heat that is generated.
If you are considering purchasing a new crane or upgrading an existing crane, I recommend that you choose a crane that is equipped with a double shoe collector. It is a small investment that can provide significant benefits in terms of reliability, safety, and efficiency.
Tips for ensuring the proper operation of a DSC:
- Regularly inspect the collector shoes for wear and tear.
- Keep the collector shoes clean and free of dirt and debris.
- Make sure that the collector shoes are properly aligned with the conductor bar.
- If the collector shoes do lose contact with the conductor bar, have them repaired or replaced as soon as possible.
By following these tips, you can help to ensure that your overhead crane's double shoe collector is operating properly and safely.
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