Caging brakes is a technique truckers use to temporarily release the brakes on a wheel when there is an air brake system failure. While not meant for normal operation, caging brakes can allow you to safely drive to a repair facility when brakes fail on the road.
This comprehensive guide will walk you through when and how to properly cage trailer or truck brakes so you can get back on the road safely.
Here’s a quick step-by-step guide:
Follow these steps to cage brakes:
- Step 1: Locate the faulty brake chamber on the wheel.
- Step 2: Back off the slack adjuster to provide clearance.
- Step 3: Remove the chamber’s hex plug, washer and nut.
- Step 4: Insert caging tool into chamber and turn clockwise.
- Step 5: Thread on nut and washer, then tighten to compress spring.
- Step 6: Tighten until brakes release on that wheel.
- Step 7: Remove tool and replace hex plug parts.
- Step 8: Drive slowly and carefully to a repair facility.
- Step 9: Notify the repair shop you have caged brakes.
- Step 10: Use wheel chocks once parked.
When Should You Cage Brakes?
Caging brakes is only meant as an emergency procedure when air brake failure occurs and you need to get to a repair shop. It is not for normal brake operation.
Here are situations when you may need to cage brakes:
- Air compressor failure leading to low air pressure
- Air lines damaged or leaking
- Faulty brake valves
- Stuck brake chambers
- Other air system malfunctions
Without air pressure, the brakes will lock up and you won’t be able to move. Caging brakes can release the brakes on one or more wheels so you can drive to a safe location for repairs.
However, use extreme caution when caging brakes. You will have limited braking capacity so reduce speed and drive carefully to a repair facility. Notify them you have caged brakes so they can take proper precautions.
How Does Caging Brakes Work?
Air brakes use compressed air to push against a diaphragm in the brake chamber, applying the brakes. When air pressure is lost, a strong spring pushes the diaphragm in the opposite direction, engaging the brakes.
Caging brakes manually compresses this spring inside the chamber using a special tool. This releases tension on the diaphragm so the brakes disengage on that wheel.
When done properly, caging brakes allows the wheel to turn freely so you can drive to a repair facility. However, you lose all braking power on that wheel so use extreme caution.
Step-by-Step Guide to Caging Brakes
Follow these steps to safely cage the brakes on a truck or trailer wheel:
1. Identify Faulty Brake Chamber
Locate the brake chamber for the wheel where brakes are stuck or faulty. On trailers, chambers mount to the axle near each wheel. On trucks, they mount to the frame near the wheels.
2. Release Brake Adjustment
- For manual slack adjusters, back off the slack adjuster on the problem brake several turns.
- For automatic slack adjusters, use the release tool to back off the adjuster mechanism.
This gives you room to work on the chamber.
3. Remove Chamber Access Plug
Find the hex-shaped access plug on the chamber clamp or mounting bracket. Remove the plug, washer and retaining nut and set aside.
4. Insert Caging Tool
Insert the caging tool into the access port and turn it clockwise until seated inside the chamber. This engages the end of the tool with the chamber spring.
5. Tighten Tool Nut
Thread the nut and washer onto the caging tool and tighten with a wrench or ratchet. As you tighten, the tool compresses the spring inside the chamber.
6. Release Brakes
Turn the nut until the brakes release on that wheel. You’ll need to tighten quite far, likely leaving only 2-3 inches of the tool protruding.
Have someone check that the wheel spins freely when done. If not, tighten more until fully caged.
7. Replace Access Plug
Once brakes are fully released, remove the tool and re-install the access plug, washer and nut. Tighten snugly.
8. Proceed Carefully!
You now have no brakes on that wheel! Reduce speed significantly and proceed carefully to the nearest repair facility. Notify them you have caged brakes so they take proper precautions.
Use extra caution going downhill and allow much longer stopping distance with your limited braking capacity.
Tips for Caging Brakes
Follow these tips for safely caging trailer or truck brakes:
- Only cage brakes on one axle/side at a time to maintain some braking ability.
- Ensure parking/emergency brakes are fully operational before caging brakes.
- Drive slowly and allow 4-6 times normal stopping distance.
- Avoid steep grades or downhill driving if possible.
- Keep an eye on brake air pressure gauge so you don’t deplete reserves.
- Notify the repair shop you have caged brakes before arrival.
- Apply wheel chocks once parked at the shop.
Frequently Asked Questions
Is caging brakes legal?
Yes, caging brakes is legal as a temporary emergency measure when air system failure occurs en route. It allows you to drive to a repair facility instead of waiting for a roadside repair.
How long can I drive with caged brakes?
Only drive far enough to reach the nearest safe repair facility. This procedure is not intended for extended driving. Have the air system fixed promptly.
What if air pressure is still adequate?
If air pressure remains within operating limits, do not cage brakes unnecessarily. The air system may still be able to stop the vehicle safely.
Do I need special tools?
Yes, you need a proper brake chamber caging tool designed for compressing the internal spring. Do not use makeshift devices. Proper tools are available at truck stops and brake shops.
What if caging doesn’t release the brakes?
If the brakes don’t release after fully tightening the caging tool, a more serious mechanical problem may exist. Do not attempt to drive the vehicle. Call for a tow.
Caging brakes is a quick emergency procedure that can get your rig rolling again when air brake failure strikes on the road. Follow this guide to safely cage brakes and get to a repair facility. But always use extreme caution when operating with caged brakes.