Dock doors cycle hundreds of times a week, take hits from forklifts and freeze in a Calgary winter. A few minutes per door each month catches most problems before a door comes down on a trailer, or stays stuck open in January.
1. Springs: look, don't touch
With the door closed, look at the torsion springs above the door. Watch for gaps in the coils (a broken spring), rust, or a door that suddenly feels heavy or lifts crooked.
2. Cables and drums
Check the lift cables on both sides: no fraying, kinks or rust, sitting properly in the drum grooves, the same tension on both sides. A slack cable on one side is a sign the door is about to bind or fall crooked.
3. Photo-eyes and reversing
On powered doors, close the door and pass an object through the photo-eye beam. The door should stop and reverse. Then check the bottom edge reverses if it meets an obstruction. Clean the photo-eye lenses and check the brackets haven't been knocked out of line.
4. Leveler hydraulics and lip
Run the leveler through a full cycle: it should rise smoothly, the lip should extend fully and fold back. Look for oil under the pit, damaged hinges or a lip that doesn't fully support. Check toe guards and the maintenance strut are in place.
5. Seals, bumpers and tracks
Torn seals cost heat and let in snow. Worn bumpers let trailers hit the building. Bent tracks and loose brackets make doors bind. Note any damage with the door number, and book the repair.
When to call a pro
- Any spring or cable problem
- A door that doesn't reverse, or a photo-eye that can't be aligned
- Hydraulic leaks or a leveler that won't hold
- A door that's been hit and no longer runs straight
Take the door out of service and tag it until it's repaired.