Roller Chains on Scraper Reclaimers
Two scraper reclaimers each with a capacity of 2500 tons per hour are used to reclaim phosphate rock and chloride slag in a harbour warehouse. The material size typically ranges between 250 and 300 µm. with a bulk density ranging up to 1,9 tons/m3.
Each reclaimer has three 100kN VBS type roller chains with 400 mm (15.7") pitch roller chain links.
Lubrication had to be minimised to prevent contamination of the client's products. Excessive friction resulted between the steel pins (EN19) and the steel bushes (EN36).
Increased wear was attributed to a lack of lubrication and the abrasiveness of the products being conveyed. This caused the pins and bushes to seize when the chain links went around the sprockets of the outer link plates.
The steel bushes of the chain were fitted with Vesconite sleeves of 3 mm (0.12") wall thickness. These were installed in November 1993 on the reclaimer transporting phosphate rock. The chain operated unlubricated.
Inspected in July 1994, after the machine had worked a million tons of product, the steel pins were polished and minimal wear was found on either the pins or Vesconite bushes.
An additional 1,5 million tons of phosphate rock were conveyed prior to the removal of the Vesconite bushes in August 1995 - nearly two years later.
The advantages of Vesconite bushes
- extended chain life 5 times
- operated well in the dirty, highly abrasive, unlubricated conditions
- increased life of the pins
- ensured better machine performance
- reduced maintenance costs
- resulted in less downtime
Updated Mar 28 2002
