Tractor throtle control - Page 1
Forum section: electronics / projects

author: gaminn
author_rank: Frequent Contributor
timestamp: January 28, 2020, 12:37:32 pm
content: Hi,I would like to control throttle of my tractor remotely. Two states are needed: "idle" and "higher rpm". A paw on the motor body will be controlled by the actuator.The actuator should travel approx 10 cm, the force needed is 10 N and voltage is 12 V.I already tried:https://www.aliexpress.com/item/4000441996425.htmlbut as this is actually not solenoid (it consists of DC motor and two endswitches) it is not fail safe for my purpose. I want the actuator to release the throtle back to the idle state when there is no power.I also tried some 12 V solenoid valve for car's trunk release but it consumes a lot of power when actuated (more than 10 amps) so it cannot be actuated for a long time (and I also have already some electronics designed for this project and it would not handle more than 3 amps @ 12 V).I also considered pneumatic actuator but this would mean a lot of work on the tractor to bring pressure air to the actuator.Are there any servos or solenoids that can do what I need?

author: calzap
author_rank: Frequent Contributor
timestamp: January 28, 2020, 08:35:18 pm
content: If your tractor has hydraulics (most do), you could use a small hydraulic cylinder. You would need an electric hydraulic valve that has two hydraulic channels or two single hydraulic channel valves.Alternately, small 12 VDC air compressors are readily available and cheap. Their intended use is for inflating tires on automobiles. I carry them in some of my vehicles. Add a pneumatic cylinder, bleed valve, remotely operated relay, some tubing, wire, fuse and maybe a key-switch for safety.I hope the system you are planning is for use only when the tractor is stationary.Mike in California

author: Gregg
author_rank: Super Contributor
timestamp: January 28, 2020, 11:31:56 pm
content: If your tractor is not diesel, it should have intake manifold vacuum that could be used for your throttle device. Early vehicle speed controls used a vacuum diaphragm to operate the throttle.

author: elektrolitr
author_rank: Contributor
timestamp: January 29, 2020, 08:39:26 am
content: Try to google "fail safe actuator" or "spring return actuator"

author: gaminn
author_rank: Frequent Contributor
timestamp: February 01, 2020, 09:45:49 pm
content: Thanks for your ideas. I think the hydraulic actuator is even more complicated than the pneumatic one. And I have diesel tractor.Meanwhile, I thought about this:The components are an electrically operated (12 V) clutch, 12 V motor (reduced to very low speed, so it stays at its current position without power even with some external force, worm gearbox will do the job I think), and normally closed end switch. The motor's shaft is connected to the input of the clutch, throttle cable is winded by clutch's outputs. The motor is connected to power via normally closed switch.With power connected, the clutch engages and the motor rotates which pulls the throttle cable. There is an object mounted on the throttle cable that will come into contact with end switch once desired throttle level is reached, the end switch opens and the motor stops.With power disconnected the clutch is disengaged and the throttle cable returns by itself.The question is - is there any suitable 12 V clutch, reasonably small. I know ACs is cars use electromagnetic clutch, but these are quite big. I think I don't need such a large torque.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 01, 2020, 10:36:19 pm
content: Quote from: gaminn on January 28, 2020, 12:37:32 pmTry turning down the voltage after it pulls in. If it will reliably stay held with much less than full voltage, a PWM circuit would be all you need.