Was away from the project for a few weeks but have come back to tackle another challenging section. The electrical panel for the retracts.
Currently I don't understand the electrical system for the retract motor. Some basics that I do understand:
1. The retract motor is designed to only turn one way. The motor turns the gear system to retract the landing gear and stops at the gearbox rotation that puts the gear in the full up position.
2. To extend, the gearbox continues to rotate past the full up position, beginning the extension of the gear legs.
3. There are upper travel switches and lower travel switches on each of the gearboxes. The trip point of each of these switches are fully adjustable. Each side works in series to set the stopping point of the travel.
4. The gear is retracted (and extended) with a push button. Pushing the button causes the retract motor to spin.
5. There are squat switches in each of the gear legs. Unfortunately the switch in one leg doesn't work and it is not accessible or repairable without destroying the gear leg assembly. Maintenance and repair wasn't considered when this part was designed.
Some design unknowns:
1. I've had the motor checked out and it appears to be in working but it requires some capacitors and such to work. There are some capacitors on the retract electrical panel but I don't know how they fit into the circuitry. I call these items capacitors but I'm not positive they are. Capacitors should have a capacitance rating on them in micro Farads. These ones don't.
2. There are some additional pieces that appear to be large diodes. How do they fit into the circuitry?
3. There are a couple of other unknown pieces. What are they? What do they do? I don't know. Yet.
4. There's a thermal relay that's part of the circuity. I opened it up and it's clean and functional. There are two separate thermal strips that when 12V is applied across either of them, the thermal strips bend away from the contact point of the circuit. In essence, each strip acts like a circuit breaker. This must trip a separate relay as the basic operation of this thermal relay would mean they would heat up and open the circuit, when they cooled they would automatically reset, closing the circuit, beginning the cycle over again. The heating cycle is very quick, within a second. The cooling cycle takes a few seconds. How and what this does, I've yet to figure out.
5. How do the squat switches fit into the circuitry? I expect they'll be in series to the retract function, but how?
Some operations unknowns:
1. Does the gear retract with the single push of the button or does it require a push and hold? One could argue advantages and disadvantages either way.
2. Do the travel switches trip a relay to cause the gear motor to stop or do those switches simply light up the landing gear indicator lights?