Owen_N
Well-Known Member
I am looking at bench dyno controls for my proposed engine.
The carb has about 35mm pull, and quite a strong spring. I need to oppose the spring so that the lever will stay in one place.
The carb spring has a high preload and low rate , so can I do the opposite at the lever end? How would this be arranged?
I had a look a boat throttle levers, but they tend to be expensive- about $122+++ NZD.
*aside*
I also want to hook the lever up to a large servo eventually, so that the loading up of the water brake can be controlled,
I think holding at a fixed rpm, say 7000 rpm, and adjusting brake flow while auto-adjusting up to full throttle at a fixed rpm.
A further enhancement is to have 2 flow valves and a temperature monitor to adjust water flow.
Further again, when the "start run" button is pressed, the engine is accelerated in a steady manner by adjusting the brake automatically.
When it hits the top target overrev, I hit the "Stop" button, and throttle goes to zero, and the brake is shut down.
This will cause a fairly rapid engine stall, but that should be OK.
Keep an emergency ignition cut button in case of engine runaway-an rpm cutout at 19,500 rpm would be a good idea.
*end aside*
I have two carbs, so I could borrow a compression spring from the other one. The spring should run in a tube, as it would be unstable sideways, I think.
The throttle pull cable can run through through the center.
The lever also needs a rotational friction drag, to make it stay put. This could be arranged a bit like a motorbike friction damper, with a friction disc, a backing disc, a finger-type cup spring washer,
and a tightening wheel on the lever pivot.
I was thinking about 6 inches lever length, with a 30 degree throw.
* Question: where could I get one of these fancy cup spring washers?
Would another backing spring layout be feasible?
I could try a search for "rotary friction damper cup spring".
What would be a better search sentence?
The carb has about 35mm pull, and quite a strong spring. I need to oppose the spring so that the lever will stay in one place.
The carb spring has a high preload and low rate , so can I do the opposite at the lever end? How would this be arranged?
I had a look a boat throttle levers, but they tend to be expensive- about $122+++ NZD.
*aside*
I also want to hook the lever up to a large servo eventually, so that the loading up of the water brake can be controlled,
I think holding at a fixed rpm, say 7000 rpm, and adjusting brake flow while auto-adjusting up to full throttle at a fixed rpm.
A further enhancement is to have 2 flow valves and a temperature monitor to adjust water flow.
Further again, when the "start run" button is pressed, the engine is accelerated in a steady manner by adjusting the brake automatically.
When it hits the top target overrev, I hit the "Stop" button, and throttle goes to zero, and the brake is shut down.
This will cause a fairly rapid engine stall, but that should be OK.
Keep an emergency ignition cut button in case of engine runaway-an rpm cutout at 19,500 rpm would be a good idea.
*end aside*
I have two carbs, so I could borrow a compression spring from the other one. The spring should run in a tube, as it would be unstable sideways, I think.
The throttle pull cable can run through through the center.
The lever also needs a rotational friction drag, to make it stay put. This could be arranged a bit like a motorbike friction damper, with a friction disc, a backing disc, a finger-type cup spring washer,
and a tightening wheel on the lever pivot.
I was thinking about 6 inches lever length, with a 30 degree throw.
* Question: where could I get one of these fancy cup spring washers?
Would another backing spring layout be feasible?
I could try a search for "rotary friction damper cup spring".
What would be a better search sentence?