How to avoid pin bushing wear and minimize repair costs

Auto Lube reduces contamination and wear of pin bushing, extend machine life and help avoid downtime.

Proper lubrication reduces excessive contamination  and wear of bronze pin/bushings. Which helps to maximize the profitability of capital equipment, ensures uptime and decreases the frequency of downtime due to costly repairs.

Today’s construction and mining equipment use the most sophisticated form of bronze pin bushings.  Their ability to reduce wear is impressive, nevertheless, a problem lies within the nature of the material itself – bronze. Bronze is extremely reliable and very durable when used as a ‘wear’ material but it is not contamination-proof. The purpose of wear materials is to reduce damage to structural steel components. The bronze bushing is much cheaper to replace than something like a wheel loader boom arm.


The effect of contamination on pin bushings is directly related to scaring, skidding/plowing and smearing. When excessive contamination builds up between a pin and bushing surface, the rotation of the pin and the pressure load starts digging contamination into the bronze bushing. When contamination keeps building up, it will restrict the movement of the pin by increasing friction

Open Lube Points

Open lube points that lack fresh grease allow dirt to easily enter the system.

Due to increasing friction and the load pressure, the pin will eventually gouge the bronze and start removing material from the bushing to allow the pin to rotate. These material deposits lead to additional contamination between the pin and bushing, making the problem even worse. If this process continues, the space between the pin and bushing will increase, leading to even more contamination and wear. When all the bronze bushing material is worn away, the pin will start digging into the steel structure of the equipment. 

Wear evolution due to contamination:

  1. Good bushing
  2. Worn bushing
  3. Worn bushing affecting the frame

Under these conditions production machinery is generally put out of service and the bushings may need to be replaced.

  • If only the bushing is damaged, the pin and bushing set may need to be replaced.
  • If the pin has damaged the structural steel of the equipment, a ‘line bore’ will probably be required, increasing the cost of the repairs exponentially.


Cost of bushing pin repairs

Replacing a damaged pin/bushing can cost from $300 to $1, 500 and is relatively time-consuming as the equipment may need to be transported to an off-site workshop. The duration of a “simple” removal and replacement of worn parts lasts between 5-8 hours if the pin/bushing is not very stuck. Furthermore, when a worn pin has damaged the structural steel of the equipment, operators are faced not only with the costs for replacing the damaged pin/bushing, but also with additional downtime and repair costs for line boring ($500 per hole), welding, and refitting.

The importance of proper lubrication maintenance

Proper lubrication can significantly help to reduce the need for replacement or repair of pin bushings. Most pin bushings today have ‘grease grooves’ on the inner diameter where applied lubricants form a film thickness for the pin to rotate on. The application of lubricants into these grooves also aid in “purging” contaminants from the bushing by forcing out unwanted materials, however, if proper greasing intervals are not maintained the groves become a house for contamination. Without proper and consistent lubrication, wear can occur because the bushings are not “purged” and cleaned frequently.

Automatic lubrication minimizes damage and costs

Automatic lubrication systems consistently dispense accurate doses of lubricant. It enables the permanent purging of contamination from the pin and bushing while the system is working. By greasing during equipment operation, the entire pin is coated and equal purging of the pin’s circumference is obtained. This increases equipment life and extends machine performance, while reducing the maintenance- and repair frequency which leads to minimal downtime. 

All this information in one overview?


Graco manufactures automatic lubrication systems specifically designed for yellow iron construction and mining equipment. Use our Yellow Iron Kit Selector to find out which automatic lubrication system is the perfect match for your installation. 


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