New throttle cable--not enough friction!

[F51]

The throttle cable broke just as we were locking through the Industrial Canal lock. We spent a few days in the marina rounding up parts and decided to change out both the throttle and shift cables as they were both the same age. The new cables are great! You can positively feel the detents on the transmission so you know whether or not the transmission is in gear. However, the throttle cable is so smooth that the return spring on the injector pump eases the throttle closed when you remove you hand from the throttle lever. I need to find a way to reduce the strength of the return spring or increase the friction in the cable. The engine is a Lehman 120 and the control is an old Morse concentric-shaft two-handle unit with no friction adjustment on the control. Anybody have any suggestions?

[NCboatrx]

Morse Teleflex make a cable brake for the 33c and 43c cables. The part # is 44386. List price is about $22.50 and this will solve your problem.
Stanley

[sy_gilana]

I had that problem on my Detroit M.E.
Cut a sheet of hdpe (starboard) into two strips 1/2 inch wide by 1 1/1 long and 1/4 thick.
Drilled two holes nylock nut and bolt inserted. Then drilled 8mm hole halfway into the crack parallel to the sides. Clamped the drilled portion on the cable outer end, and then adjust bolts to brake the cable inner.

[Blue Stocking]

Some of the old Morse, 2 lever concentric type, have a screw-retained, spring loaded detent ball at the 6 o'clock position. Tighten to lock the throttle. Mine did.

[ggray]

I have what NC Boat must be describing, clamped just below the levers.

It looked rather crude, like a backyard mechanic devised it. But once I thought about it, it made sense. Should the cable break--and most of its length is between the clamp and the engine, the spring at the engine would pull the "throttle" to idle.

[Rex Delay]

Get a wire rope clip (cable clamp) the size of your cable and install anywhere along the length of the cable and tighten it until you like the friction. Cheap, simple, works.

[40 South]

What about a spring to assist the throttle cable acting against the return spring. It could be tensioned as required by length. Readily available from most hardware stores.

[daddle]

On one engine I simply removed the external speed control spring. On another I added a external spring. Friction is somewhat counter-productive since you have just spent good money on low-friction cables. There's is no real need for a return spring on a diesel in case of cable failure. It will not over-speed. You can always use the STOP control.

[TrentePieds]

A clamp on the throttle cable sheath seems to be the common method of "frictioning" the throttle. Crude but effective, if a little ticklish to adjust. And cheap :-)

In TrentePieds getting into the binnacle is a PITA. Therefore the clamp is right next to the level on the injector pump. That's okay cos the "free" part of the cable, twixt the clamp on the cable-sheath and the lever, has no friction, and the "captive" part of the cable, twixt the clamp and the throttle lever, cannot buckle when under pressure cos it's contained within the sheath.

TrentePieds

[ggray]

Yes, but with your setup, the cable is more likely to break "upstream" of the clamp, so engine would remain at the speed as of the moment of breakage.

I'm considering Daddle's first suggestion. But first, I'd check if pulling the shut down will do so if at WOT.

[TrentePieds]

@ggray #10

I agree - so it is. However, in TrentePieds there isn't really a choice, and it doesn't worry me particularly since cable breaks are exceeding rare and the warning symptoms of an imminent cable break would be obvious. You would know of impending problems at start-up.

On my Vetus - which is a Mitsubishi tractor engine - the shut down is a "normally open" valve within the pump. Closing that valve will kill the engine at any RPM including WOT. It is solenoid operated with manual override. The override is of necessity situated right on the pump body and therefore awkward to get at. I have wired the solenoid to a button in the cabin so, if necessary, I can stand back from the engine casing and kill the engine without going on deck as well as from the cockpit steering position. But my reason for making that modification is that I have no faith in the pretty-pretty little toy buttons in the Vetus control panel in the cockpit. The cabin mounted button is a grown-up Perko.

With the clamp on the cable "backed off" the control lever goes to idle. Sensible enuff of Mitsubishi to make idle the "default". I imagine that all engine manufacturers do that, but it'd be easy enuff to verify on any installation.

TrentePieds.

[RobMinton]

Originally Posted by Rex Delay

Get a wire rope clip (cable clamp) the size of your cable and install anywhere along the length of the cable and tighten it until you like the friction. Cheap, simple, works.

This is simply brilliant. Thank you for the suggestion.

[groundtackle]

I've found placing the clamp close to the lever is important. If installed at the engine end compression will make it snake inside the sheath giving you poor feel. In tension it can drag the sheath out of the swage as those ends aren't really intended for that purpose. Bulldog or wire clamps work great, in stainless they are inexpensive, small and can be accurately adjusted.
Chris

[RobMinton]

Had a small SS hose clamp in my spares jar. So far so good. It adjusts easily and is readily accessible for inspection and future adjustment.