What are the common faults of cam brake short shaft?

1、 Cam and camshaft (short shaft body) malfunction
a. Wear and groove formation on the working surface of the cam
Long term friction results in flattened cam profiles, grooves, increased braking stroke, insufficient braking force, and soft braking; In severe cases, the cam lift is insufficient and the brake cannot be opened.
b. Camshaft bending and deformation
Overloading and intense braking impact result in short axle bending, unsynchronized left and right braking, brake deviation, and uneven wear of brake shoes.
c. Camshaft spline wear/rolling key
The spline connecting to the brake adjustment arm is worn and slipping. When the brake adjustment arm is pressed, it rotates but the cam does not move, resulting in no braking.
d. Camshaft jamming and inflexible rotation
Rust, sediment ingress, lubrication failure, difficulty in cam return, brake drag, wheel overheating, and abnormal tire wear.
2、 Fault in bearings and bushings
a. The lining is worn and loose
The wear clearance of the camshaft bushing is too large, causing radial shaking of the cam during operation, unstable braking, and loud noise.
b. Bearing erosion and damage
Lack of oil, water ingress, bearing locking, cam unable to rotate, resulting in dragging or direct braking.
3、 Seal failure
a. Oil seal damage and leakage
Lubricating grease leaks and is thrown onto the brake shoe friction plate → The friction plate is stained with oil, resulting in a significant decrease in braking force and brake slippage.
b. Dust cover damaged
Muddy water and dust enter the cam chamber, accelerating the corrosion and wear of the cam and lining.
4、 Brake shoes and related malfunctions
a. Wear and breakage of brake shoe rollers
The roller is a force transmission component that drives the brake shoe with a cam. After wear, the clearance increases and the braking response is delayed; Broken and stuck rollers can cause dragging and braking.
b. Fatigue fracture of brake shoe return spring
The spring fails, the shoes cannot return to their original position, and there is continuous dragging and grinding, resulting in high temperature in the wheel hub.
5、 Installation and adjustment related faults
a. Adjust the arm gap imbalance
Excessive clearance: brake lag, weak braking force; Gap too small: Continuously drag the brake.
b. Short axis fixed seat cracked
Repeated braking impacts, bracket cracking, and displacement of the entire cam mechanism pose a high risk of braking failure.
6、 Quick response to typical fault phenomena
-Long term heating of the wheels → Cams stuck/Return springs broken/Clearance too small
-Brake deviation → unilateral cam wear, short shaft bending, roller damage
-Brake weakness, large stroke → cam wear, loose lining, friction plate wear
-There is a strange noise when braking → the roller is broken, the clearance between the lining is large, and the cam is grooved
-Sudden loss of braking → spline rolling key and adjustment arm failure