Is there a burning smell coming from your overhead crane? Do you see smoke rising from the brake drum? Or maybe you’ve noticed the paint on the brake wheel is starting to discolor or peel?
If so, you have an overheating brake.
Heat is the natural enemy of any braking system. While friction generates heat by design, excessive heat is a sign that something is wrong. If ignored, it leads to “Brake Fade” (loss of holding power), glazed linings, and eventually, total failure.
Before you panic and order a whole new system, check these 3 common culprits. 90% of the time, the problem is simpler than you think.
Cause 1: The “Dragging” Brake (Incomplete Release)
This is the #1 cause of overheating. It means your brake isn’t opening fully. Even if it looks open, the brake pads (linings) might still be lightly rubbing against the spinning drum. This constant friction generates massive heat in minutes.
Why it happens:
- Thruster Issues: Your electro-hydraulic thruster (e.g., Ed series) might be low on oil, have an air lock, or the internal seals are worn. It’s pushing, but not hard enough to fully open the arms.
- Voltage Drop: If the power cable is too long or thin, the voltage reaching the thruster might be too low to generate full force.
The Fix:
- Check the hydraulic oil level in the thruster. Top it up if needed.
- Watch the thruster rod movement. Does it extend fully and quickly? If it’s sluggish, it might need a rebuild or replacement.
- Check the voltage at the thruster terminals while it’s operating.
Cause 2: Improper Shoe Clearance (The “Uneven Gap”)
Ideally, when the brake opens, both brake shoes should pull back equally, leaving a nice, even gap between the lining and the drum.
Why it happens:
- Misadjustment: If the tie-rod is too tight, the total gap is too small. As the drum heats up and expands, that gap disappears, and the brake starts to bind.
- Stuck Pins: If the hinge pins are rusty or lack grease, the brake arms can’t move freely. One side might open wide, while the other side stays stuck against the drum.
The Fix:
- Inspect the Equal Retreat Device: Most modern brakes (like our YWZ series) have a mechanism to ensure equal clearance. Make sure the nut hasn’t vibrated loose.
- Measure the Gap: Use a feeler gauge. You typically want about 0.7mm to 1.0mm clearance on both sides (check your manual for the specific model).
- Grease the Joints: A little lubrication on the main hinge points goes a long way.
Cause 3: Operational Abuse (Too Much “Jogging”)
Sometimes, the hardware is fine, but the operation is too aggressive.
Why it happens:
- Jogging/Inching: Operators often tap the button repeatedly to position a load precisely. Every time they tap, the brake opens and closes.
- Exceeding Duty Cycle: Standard industrial brakes are rated for a certain number of operations per hour. If your crane is doing high-frequency cycles (like in a busy scrap yard) with a standard brake, it simply doesn’t have time to cool down between stops.
The Fix:
- Check the Lining Material: If high heat is unavoidable, you might need premium, high-temperature friction pads (non-asbestos).
- Operator Training: Encourage smoother operation.
- Consider a VFD: Installing a Variable Frequency Drive allows the motor to do the slowing down, so the brake is only used for holding. This drastically reduces heat.
Summary
An overheating brake is a warning signal you shouldn’t ignore.
- Check the thruster (Is it weak?).
- Check the gap (Is it rubbing?).
- Check the operation (Are you working it too hard?).
Need replacement brake shoes, a new thruster, or technical advice? Don’t wait for failure. [Contact HMIC today] and let us help you keep your cranes running cool and safe.
