Apron Feeders Support

Download the Apron Feeders Troubleshooting Guide

McLanahan Corporation’s Apron Feeder Troubleshooting Guide can help you find probable causes for situations that may arise when operating this equipment, including what to do if the flight bolts break and how to handle a stalling feeder.

Apron Feeder Maintenance

When should I replace the flight?

Replace the flight when:

  • the middle sags 0.25" or 7m
  • the groove wear at the flight end is 0.25" 7mm in flat skirting area 
  • when the flight is straight and wear in the center area is 0.375" on cast flights or 0.3125" on formed flights

How big should the gap between the flight and the impact rail be?

The gap should be between 0.125" and 0.25".

How do I measure wear on the return rollers?

  1. Clean the area to be measured.
  2. Using a caliper, measure the diameter where the flight rides.
  3. Measure the distance between the tips of the caliper.
  4. Take at least three measurements in three different places and calculate the average.
  5. Measure both sides of the feeder.

For FL4, FD4 and FD7 models, a measurement of 5.12" or 130 mm indicates 50% wear, and a measurement of 4.72" or 120mm indicates 100% wear. For FD9 and FD10 models, a measurement of 8.62" or 219mm indicates 50% wear, and a measurement of 8.23" or 209 mm indicates 100% wear.

What is the maximum sag for Apron Feeder chains?

The maximum sag for Apron Feeder chains is 1.75" or 45mm. On horizontal installations, the sag will be between the return roller. On Apron Feeders inclined up to 25 degrees, the chain sag might appear only at the tail shaft.

How do I measure the track's internal wear?

Track internal wear is measured by determining the pitch extended over four adjacent sections with a tape measure calibrated in 0.02" or 0.5mm increments. The track and tape must be stretched tight and straight to obtain an accurate measurement. The reading must be made from one side of a pin to the same side of the fourth pin away. The hook on the 0" or 0mm end of the tape should not be used. This measurement should be taken at least three sections away from one-piece type master joints and should be repeated at least twice over different sections of the track on both sides of the machine.

Operational Best Practices

Can I operate the Apron Feeder in reverse?

Operating an Apron Feeder in reverse should only be allowed at a much slower speed and torque. This operation should not be done with material in the hopper. The Apron Feeder and Hopper will suffer. This should only be for maintenance.

Should the Apron Feeder chain be loose or tight?

Running a loose chain is much better than a tight chain. Tight chains will bend head and tail shafts with every rotation and require more horsepower to operate empty, thus using up energy that should be used to move the material. The chain must sag at least 25mm between the return rollers.

What is the proper direction to run the chain?

The proper direction of the chain is when the pin turns inside the bushing as it travels around the head and tail shafts. If the chain travel backward, the bushing will turn as it meshes to the drive sprocket, causing premature wear to the bushing and the sprocket.

Recommended Spare Parts

McLanahan Corporation recommends that you keep certain replacement parts at your facility for your Apron Feeder(s).

Part Name


Carry Roller1
Return Roller 1
Sprocket for Dozer Chain Flights2

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Apron Feeders

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