factory low price ASTM A325 Heavy Hex Structural Bolts Supply to Rotterdam

The STM32 Discovery dev board is used to read an SPI serial interface magnetic absolute angle sensor and drive PWM and DIR signals to an H-bridge for a brushed gear-motor directly coupled to the weighted base. Sample loop is 1024 Hz and the PWM frequency is approximately 8 kHz. A brass and PTFE composite thrust washer is used between the gearbox face and the 6061 aluminum hub of the weighted base.

The beam is dual-ball bearing mounted on a 3/8″ vented cap screw, which is fastened to the rotating platform with a nylon insert lock nut. The vented cap screw allows signal wires to pass through to the angle sensor fixed at the other end of the mount screw. Neodymium magnets are fixed to the beam on an aluminum bracket over the angle sensor.

The gearbox has experienced accelerated wear, likely do to half of the planetary gears being nylon despite being specified in the sales literature as metal. It has been rebuilt several times, with thrust washer moved in the gear stack, and exhibits a “detented” non-linearity while rotating. The PID must compensate for this as well.

The Raspberry Pi is used to update PID loop gains through an SSH terminal WiFi user interface, and generate live plots of the angle and PWM data using gnuplot and NGINX web server. Wireless interfaces allow for full continuous 360 degree rotation to balance the beam.

The Raspberry Pi and STM32 Discovery communicate using bidirectional UART serial. Processing is otherwise completely independent and parallel.

The project is used to demonstrate Zigler-Nichols and other PID tunings. The coefficients used are from the Wikipedia article on Zigler-Nichols tuning method.

Video tutorial on the 3 different ways on how a drum brake assembly can stick on. Having the drum brake assembly stick on can mean either the vehicle won’t move or it will create an excessive amount of heat damaging multiple components in the process. You may also see poor acceleration, poor braking performance, the vehicle pulls to one side, or an increase in fuel consumption.

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Tools/Supplies Needed:
-standard screwdriver
-wheel wrench
-jack
-axle stands
-any required replacement parts

Procedure:
The wheel cylinder can become seized:
-over time these may becoming rusty or filled with dirt which is usually a result from failing boots
-wheel cylinder has both a front and rear piston, therefore two in total
-either one or both pistons can become seized
-to determine if the wheel cylinder faulty, you should be able to push the pads inward from one side to the other if the pistons aren’t bottomed out
-if not, then have a second person, being extremely careful, lightly depress the brake pedal
-do not got too far as you do risk pushing the piston out completely
-in order to remove the drum, the automatic adjust can be backed off through the small hole in the backing plate
-if that fails, then you may need to cut the hold down spring pins on the backing plate or remove the wheel cylinder completely
-as for repairing the issue, you can rebuild the wheel cylinder yourself, have someone rebuild the unit for you, or purchase a new replacement

A stuck emergency brake:
-other emergency brake cables can become filled with dirt or rust which will prevent them returning to their freed position
-this can happen to both vehicle which never have the emergency brake used or ones which are used all the time
-normally if they are used, this does reduce the risk of them sticking
-this can happen to one side of both sides of a vehicle
-if you recently applied the emergency brake, then this could possibly be the culprit
-if not, then the issue does not relating to the emergency brake assembly
-if you try to apply the emergency brake, depending on the assemblies design or if there is an issue with both cables, you won’t feel tension on the lever
-another reason for not feeling tension on the lever is if the emergency brake is in need of adjustment
-to repair or assist in the repair, sometimes you can reverse the vehicle which will push the shoes back
-but this only works in a mild situation
-other times the cable can be giggled to reduce the tension or back the automatic adjuster off
-as a final solution, cut the emergency brake cable directly behind the drum brake assembly
-considering the cable or cables are faulty, they will need to be replaced regardless
-even if you did manage to get the cable to return, the issue will return again

The final issue can be caused by rusted brake shoes:
-this normally happens if a vehicle can been sitting for a longer period of time and will also depend on the composition of the shoe braking material
-this won’t cause drag on the drum, but rather the drum to stick on completely and the vehicle will not move or at least the wheel won’t
-in a mild situation you should be able to drive the vehicle in reverse which will break the shoes free
-driving forward will most likely not work as the drum brake assembly is self energizing and will only push more against the braking surface rather than just allowing the drum to rotate
-in a severe situation, you will need to disassemble the drum brake assembly backing the automatic adjuster off, then either using a puller or cutting the hold down pins
-then replace any parts as needed

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