720 inner spring disc brake

What to do if the front fork makes a clanging sound?

Experienced drivers who run urban and rural freight are afraid of a kind of abnormal sound - the front fork makes a "clang" sound when passing over speed bumps, and the handlebars shake left and right. Not only does it make the shock absorbers sound like drums, but the buffering of the spring shock absorber is also discounted. The electric tricycle wheel tire has been worn out in two months, and even the screws of the motor bike triple clamps are loosened. Brother Li, a vegetable wholesaler, sighed: "When pulling a vegetable basket across the railway crossing, the front fork shakes as if it is about to fall apart, and the cucumbers in the basket can be broken in half!"

Our front fork clamp is played with "micron-level bite"! The main body is forged with 40Cr alloy quenched and tempered steel. The temperature is deliberately set at 850℃ during quenching to make the steel grains as fine as flour, and the torsional strength is 40% higher than that of ordinary 45# steel. The most amazing thing is the locking structure: serrated anti-loosening gasket + double nut bite, when tightening, you have to use a torque wrench to clamp to 38N·m, and listen to two "clicks" to be in place. The fork shoulder contact surface grinder was milled 3 times, and the gap measured with a feeler gauge was less than 0.01mm, just like a mortise and tenon structure. The actual measurement was that the wheel tire eccentric wear was reduced from 2mm to 0.5mm when pulling 1.5 tons of cargo over continuous speed bumps, and the screws of the triple clamps have not loosened once in half a year.

Three tricky designs

① Sawtooth locking black technology: The tooth angle of the anti-loosening gasket is specially made into 75°. The more it vibrates during bumps, the tighter it gets. It is 3 times more effective than ordinary flat gaskets in preventing loosening;

② Temperature difference compensation groove: A 0.5mm fine groove is milled on the side of the fixture. When the steel shrinks at -20℃ in winter, the gap can be automatically fine-tuned to avoid cold cracking;

③ Diversion anti-rust layer: A layer of nano-ceramics is sprayed on the outside of the galvanized layer. Rainwater flows down along the curved surface, and even rust is hard to find in the gap.

Maintenance secrets of old masters

1. Listen to the sound to determine tightness: If you hear a "clicking" sound when going over a bump, quickly use a torque wrench to increase it to 35N·m (tighten the standard wrench to the bottom and then back off half a turn);

2. Check the tire to adjust the fork crown: When the inner side of the Wheel Tire wears faster than the outer side, loosen the clamp screw, push the front fork back 1mm and then tighten it;

3. Fill the gap with butter: Use a syringe to apply butter to the clamp joint every month, especially after rainy days, which can reduce the risk of rust to less than 10%.