Throttle Cable Corrosion Testing

[Pbfoot1]

I am investigating using a throttle cable for a certain application. It is critical that the cable operate with a puling force. The cable may be at rest for up to 25 years in a variety of installations. Although the cable will be inside a conduit, the conduit has a small opening (1/16" wide across a 3/4" diameter) exposing the cable to the elements.

I am looking for ASE, ASTM, or the like tests to subject the cable to prove out it's corrosion resistance. The cable is currently specified to be 304 stainless steel housed in a stainless sheathing. I thought automotive brake or throttle cable would be ideal or perhaps marine throttle cable.

I look forward to seeing feedback.

 

[dgallup]

A lot of motorcycle cables are teflon lined. You can get ones with little rubber bellows on each end. Still not too sure it will work after 25 years.

How much force? Low much can it change? Low long is the cable? What exposure?

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[Pbfoot1]

As new, around 3 lbs, but expect to have an increase over time and will anticipate up to 16 lbs. The item could be used along coastal applications around salt water as well as inland. They will not be submersed in salt water.

 

[hydroman247]

304 stainless will not resist coastal air with all that salt around.

25 years is a long long time to rely on a few thin strands. If you can completely house it, avoid air flow around it and coat the thing in marine grease, including down the actual casing. This is how it is done in the marine industry but nothing is expected to work for 25 years. Nothing critical anyway.

 

[Pbfoot1]

Thank you for the input hydroman247, what I have explained is worse but due to neglect I believe the situation can occur. Focusing on worse case, I am interested in the tests developed or used by companies specifying cables within the auto and marine industry. I am in the PA/NJ area still driving a 20 year old pickup with the original parking brake cable. It is rarely used but still in one working piece, although now that I said this it is sure to break the next time I use it, and has been subjected to the salted roads and rain during this time period. What tests were used to evaluate the cable for these conditions? Is the widely used ASTM B117 good enough?

By the way, my situation better replicates the conditions of a throttle cable without the excessive underhood heat. Not directly exposed to splash.

 

[BigClive]

I have no detailed knowledge of marine matters - but what about outboard motor throttle and steering cables etc.? I think the steering cables are stainless.

 

[hydroman247]

My knowledge on this subject is purely from working with outboard engines. Smaller ones just use SS throttle cables and are a semi consumable item. If it is used in salt water, they would be replaced annually ideally. Of course many last longer but it is not the sort of place you want to be with a broken throttle cable.

I don't know about regulations since I was never involved in the manufacture or testing of such things.

 

[MikeHalloran]

I've glanced at the installation of a couple of fire protection systems, which on reflection seem representative of the duty you have stated. They had galvanized cable run with considerable clearance in straight galvanized conduit, with galvanized pulleys at every corner. IOW, no sliding fits to seize, shrink, bind, or corrode.



Mike Halloran
Pembroke Pines, FL, USA

 

[IceStationZebra]

I was thinking along the same lines at Mike. You need to use a design that is corrosion tolerant. ISZ

 

[Pbfoot1]

IceStationZebra and Mike Halloran,

The components will be corrosion resistant. I may take it to the extreme and coat stainless cable with teflon. My largest issue at the moment is determining the corrosion tests to prove it out. I am currently looking into a 30 day SO2CO2 and 10 day 20% salt spray. Will this be enough? I was interested in the tests that outboard motor companies use to prove out their cabling throttle systems.

 

[MikeHalloran]

You are being incautious, using a phrase like "prove out" WRT extrapolating a 30 or 40 day test to a 25 year service life. ... especially given that you have already been told by experienced hands that your putative material selection is unlikely to succeed.

IMHO your time would be better used prowling industrial junkyards and old installations of infrequently used equipment, studying and photographing how time has ravaged a lot of good ideas, and paying extra close attention to the population of mechanisms found still operable.

I think that within that latter population you will find a lot of large clearances and hot-dipped zinc. ... but you should check.



Mike Halloran
Pembroke Pines, FL, USA