Too much time on my hands. How bout using a DPDT center open mon on-off-on (steering arm mounted switches..one each side) and a fast 12v strong actuator with 2 normally open relays, 2 norm closed relays and 2 limit switches per foot peddle. DPDT controls actuator(one each peddle) in and out (actuator centered half extended) auto centers when you let go DPDT thumb switch...via limit switches powered by normally open relays (one each way) these triggered by normally closed relays which are also controlled via the DPDT thumb switch? Normally closed relays with limit switches insure actuator centers at half way out. When DPDT switch is pushed ...limit switches are de-energized allowing travel in and out. with DPDT centered (off) limit switches energize and recenter actuator. Well? crazy or a tinkerers idea. I dont really like foot controls...makes ankle joints sore after a while. Worth a try or am i crazy as hell for even thinking it? DPDT switches provide direct power to actuators with Normally open relays providing the power for re-centering actuators. Limit switches control normally open relays (signal/control). Normally closed relays only providing Power to the normally open relays. No power to relay = no workee regardless of limit switch signal to relays. would in theory operate as follows...push thumb switch up ^ to raise boom ..push down v to lower boom. Push other thumb switch ^ to curl bkt up...down v to dump bkt.
My first thought is that it wouldn't be worth it. Here's why, with on/off switches, you are going to be limited to one speed for boom up/down and one speed for bucket curl. That would suck. If it's slow enough for fine work, it's going to be way to slow for everything else. If it's faster so that you aren't waiting forever to dump or lower, it will be too fast for the fine control. Switches are on/off. Hand controls need to be variable speed. You'd really need servos and rheostats. Not sure what kind of machine you are talking about here, but if they offered a hand control version of the machine, maybe you could swap in the right parts or fabricate your own linkage and handles?
I agree with phil, without the ability to modulate the valve, this would be very frustrating to run.
Looking at my design, i see i could delete 1 normally off relay and still work...however just because you can do something...doesnt make in practical to do in the first place.
Fun to think of : Modulation of the valve is key to make it usable. But it doesn't have to be continuously variable. A simple foot control to make it a two step. Normally slow for precision, but switch to full flow. Work like an accelerator pedal for the boom & roll.
It has been done for years on Timberjack and now John Deere cut to length systems. Problem is all the functions are computer controlled. Cat also did starting on the 365B excavators. No oil in the cabs. Potentiometers and PWM switches tell the computer what you want and then control the valves. It's the beginning of the Terminator 1000.