Remote throttle/injection pump control?

[Darren]

I have a 1999 Kubota L3710 Hydro with all of 600 hours. The throttle has always been stiff. It consists of rods and levers that eventually transfer the motion to a push on a long rod which acts on a lever to control the injection pump. It turns out Kubota welded instead of bolting the bracket that holds a rod with a lever welded on the end. The lever on the rod apparently gave up some time yesterday when I noticed the throttle lever moving much farther than normal. The bracket is close to being inaccessible. Because the bracket is welded onto the stamped plate which holds virtually everything from the instrument panel to the steering, Kubota only wants $1,100 for the plate which includes the rod with the lever welded to it.

The rod which is linked to the injection pump works fine. It comes through the a hole in the previously mentioned plate. Anyone got any thoughts on how to operate the injection pump without the levers and rods? Rube Goldberg would have been envious of Kubota's Mickey Mouse setup.

 

[Darren]

I've been looking at the vernier locking control cables. Those seem to work on a pull basis when I need something to push. Any ideas? I don't have enough room to get the bend radius to do a 180 and come back towards the front of the engine to operate the injection pump.

 

[CJONE]

Most injection pumps have splines where the lever attaches, could you move the lever 180 deg and make it a pull set up for a Felstead cable? CJ

 

[del10820]

If you have room a bellcrank to change the pull to push might work.
Del

 

[Darren]

I'm looking at an aircraft throttle control cable which is the right length, 36", and has push pull capability. I have to measure how much force it takes to operate the lever on the injection pump.

McFarlane Aviation Products

 

[bigdeano]

McMaster has push pull cables probably at a lower price than an aircraft place.

 

[Darren]

Using a bell crank means I have to fab a custom bracket that's stiff enough not to flev. A push-pull cable eliminates the need o reverse the direction. There's plenty of places that will make up a custom length cable. As far as I can tell they're all pull cables only unless I'm missing something. Three feet is a very short cable.

 

[bigdeano]

These are push/pull

McMaster-Carr

 

[Darren]

These are push/pull

McMaster-Carr

Thanks! I had looked at those. All of them are too long. I only need a cable 3' plus the ability to lock in the setting.

 

[Darren]

I've posted this to show a temporary fix for the broken throttle linkage on a Kubota L3710. The hole the injection pump actuation rod passes through had to be elongated to the right, looking forward, to allow the mechanism to be shifted to the right to clear the brake actuation rod. Once I figure out how to mount a push-pull cable, I'll replace this. Adjusting engine speed requires reaching under the brake pedals and twisting the socket. It's awkward but it works well and allows incremental control of the engine speed. Operation is much better than the original throttle control which was always stiff.

Parts used included two nuts on both ends of the all thread with a socket epoxied on, a i" pipe cap (drilled and tapped), a 1" close nipple with a bushing epoxied in for additional support, a 1" coupling, a 3/4" to 1" bushing, and a die cast conduit fitting with a washer epoxied on for additional strength. The washer on the left was not used due to not enough threads on the die cast fitting.to tighten up the bushing. The all thread was shortened to clear the brake pedals when applied but still allow the 2" of stroke needed for the full range of movement available on the lever attached to the injection pump.

When the pipe cap was drilled there was only 1/8" of material to tap for threads. This picture shows the material added for additional depth/threads.

This shows the bushing added in the close nipple to provide additional support for the all thread operating rod. Bushing end goes toward pipe cap.

This shows the conduit fitting with the washer epoxied on. This side is on the engine side of the :fire wall and faces towards the front of the tractor. The conduit fitting is the weakes link. It won't take much side to side or up and down force before breaking. The setup requires it to withstand tension only.

This is the partially assembled mechanism showing the double nuts on the operating end with the end nut on the right forming a cup to capture the rod actuating the lever on the injection pump. All nuts and fittings had Permatex applied to the threads.

View of the mechanism in place showing how much of the pipe coupling had to be ground away to clear the brake actuation rod.

Another view of the mechanism showing the relation to the brake pedals. When the brakes are set the pedals clear the mechanism.