Differential Lock. Help Me Out Would Ya?

G-Town, I've got a question regarding this statement you made in another thread...

Just use caution to never engage or disengage the differential lock while the truck is moving.

I've considered this as one of those longstanding myths among truck drivers. Can anyone show me a statement in their current truck's operating manual that backs this up? I have heard truck drivers saying this for years, but I don't see evidence from the manufacturers that backs it up.

I'm not trying to stir anything up, but I enjoy busting up some of these myths that keep hanging around. I may be wrong, but I also enjoy learning something when I am wrong.

Thanks for any input on the subject!

My switch says "do not engage during spinout". now i have to look in manual.

"Spinout" is different than being in motion.

I'll add another question to this, since it is related.

I remember locking differentials on farm tractors. When engaged, turning was almost impossible. Is it the same on today's trucks? Remember, I'm old, so hopefully technology has changed

Great question Old School! I usually engage it when moving as well so I'd love to know if I'm doing it wrong.

Grumpy Old Man asks:

I'll add another question to this, since it is related.

I remember locking differentials on farm tractors. When engaged, turning was almost impossible. Is it the same on today's trucks? Remember, I'm old, so hopefully technology has changed

Nope, doesn't make it hard to turn at all.

In the rare occurrence that I use the lock, I engage it while moving. It's only slippery situations that prompted me to use it, and to come to a full stop to engage would cause me to lose all my momentum. A slight lift of the throttle to release any tension, and she slips right in smoothly.

Rainy’s answer is correct. I never read the fine print below the words DO NOT ENGAGE WHILE THE WHEELS...etc.

I am wrong. Partly myth, here is a link to the page in the Cascadia manual...

Differential Lockout

Thanks for the link G-Town!

It does say "engagement can be at any speed, provided the wheels are not slipping or spinning." That confirms what I was thinking. The wording is a little convoluted because of the word "spinning." I guess "spinning" carries a different connotation than rolling. Spinning refers to spinning out, as on ice.

See, I enjoy these types of discussions . It's easy for some of the little details we deal with on a daily basis to sometimes grow legs of their own and nobody actually knows the truth. I enjoy Busting A Myth every now and then.

Well...I bought into this myth since 1979. Of course back then it might have been true.

Common sense..,if you cannot engage it while moving, half of it’s intended purpose is basically useless.

Sorry for any confusion I may have created.

No problem.

Now that we've got that settled I expect to see a lot more trucks on the side of the road with torn up rear ends. Everybody's gonna be flipping that switch while they're flying down the highway just to see if it works!