Interaxle lock
 

Can someone tell me the proper use of the inter axle lock? My mechanic told me never to drive over 25mph with it on, it's only smart to use it when in a yard backing up or starting out.

A tow truck guy told me I can use it when on ice or snow, especially when trying to slow down with the engine brake on.

Advice please.

I thought you could get them a little over 25 with it on but i know its a pretty low limited speed and it will burn the differential up if you abuse it. I have never locked one in for anything other than trying to bang my way under a heavy trailer on really really slick snow covered lots. I am sure others have used it for more but thats the only thing i have ever used it for. Just my 2 cents but I cant even think it would be a good idea for you to throw the jake on if its that slick anyway,maybe get away with it if you are pretty heavy but if you are empty and on ice....cant say the jake is a good idea even if you have the diff lock kicked in. Maybe i'm wrong on that chime in if you disagree.....I'm no experet...just dont seem like a good idea

I'll lock it up when driving on slick roads, never over 35 and never using the Jake, but as Jager said that's due to the slick roads not the fact that the interaxle is locked.

Many people think that locking the interaxle gives you power to both axles which is incorrect. You've always got power to both axles. However, if a wheel starts spinning and you're unlocked all the power is transferred to that wheel, meaning you don't go anywhere until that wheel regains traction. With the interaxle locked in, there is no power transfer so the rest of your wheels stay powered. Common sense tells you which is better in slick conditions.

My book and Western Star both told me I can lock the differential in at any speed and go as fast as I want. There is no restrictions. I've used mine many many times at speeds greater then 50 turning it on and off. Maybe other rear ends are different but I'm looking at my manual right now.

I'm not gonna argue with you on what your truck manual says but that is very contray to everything i have ever heard or been told by my companies. I guess it can be different on different trucks....but all 3 companies i have been with, we have been told not to do that.....on 3 different brands of trucks. Maybe they are just overly cautious.
Steve, i do have a question though.....if you were driving in something that was slick enough that you felt you needed it.....what were you doing going in excess of 50 mph....not trying to be a know it all traffic cop...but that seems kinda contrary to conditions, maybe i am just a grandma driver when its that slick.

The main concern is: Never engage the power divider lock when a wheel or wheels are spinning!

That would be the equivalent of jamming a transmission in gear while stopped without depressing the clutch.

If the truck is stopped, or if the truck is moving with no wheel spin, you can lock and unlock the power divider lock whenever you want, as there is no relative motion between the sliding clutch teeth which engage the lock under those conditions.

Don't forget to disengage the lock when driving under normal conditions on dry pavement, or the rear axles will experience "torque windup" due to the drive wheels attempting to turn at different speeds when steering and turning corners. (this is similar to what happens if you drive a 4WD pickup on a hard road in 4 wheel lock).

Instructions for the inter axle lockout/ Power divider. Provided by Eaton Dana.

http://www.roadranger.com/ecm/groups..._axdr-0126.pdf

There also is a differential lock that locks the rear ends side to side. This is usually not installed on an OTR truck, but can be. This will be a seperate control from the power divider. This is the one you can't use over 25mph, and trust them when they say you will have severe understeer with it on.

Instructions for differential lock, Provided by Eaton Dana
http://www.roadranger.com/ecm/groups..._axdr-0130.pdf

Thanks Dweller. I was just going to say screw it and go my merry way and let everyone tell stories instead of actually PICKING UP A MANUAL AND ACTUALLY READING IT!!!!!!!!!!!!!

the only time i use my axle lock is when i am stuck in the snow ice sand or mud i use it to get me moving then i flip it off because i dont want to tear up my equipment 8)

Re: Interaxle lock
 

the switch plate on my axle lock says.. shift at any speed except if a wheel is spinning.

I dont think anyone told any STORIES....we are going by what we have learned and were told, if this qualifies as making up a story...sorry I didnt mean to lie to you all even though i didnt know i was making it up and lying.

I am still curious just as to why you would lock that in going over 50 mph if you thought it was actually slick enough to use it. This is not a smart ass question I am just very curious about this....maybe i can learn a new thing or 2 about driving in slick conditions on this thread.

last winter, I was driving on a 2 lane road in the middle of nowhere about 11 at night, the weather was dry and the road looked fine, when I went to slow down for a curve, my tractor started to go sideways. I recovered and and then I locked in the axles. I figured there must be icy patches, I dont know if it did any good to turn it on, but it made me feel better. then I went on to the customer and got stuck in the snow on the rxr tracks, (luckily, their private tracks) but that's another story

Ok, I went and got out the old freightliner manual....different things for different rear ends and traction control devices....the only one in my manual that specificly says its ok to kick in at any speed is the Dana Spicer axles with Controlled Traction Differential.

On the other hand, Dana Spicer Interaxle Differential Lockout, different from controlled traction differential, specificly states, Engage only when stopped or at slow speeds and never on dry pavement or for prolonged periods of time.

On Meritor, the one that states specificly that you should lock in only at a stand still and never over 25 mph is the [b]Main Differential Lock[/b, different from Interaxle Diff lock whichis i guess what we were thinking about on the beginning of the thread.

The only one in the manual that specifies that it is ok to use at any speed is the Dana Spicer with Controlled Traction Differential which is apparently a different thing from interaxle diff lock.

Long story short, everybody was part right and part wrong...just depends on which option your truck is equiped with.

The one constand with all of these things is that none of them are really recomended for exteneded use and nver on dry pavement...and they do cause extra wear on the drive train....So Just take a peek in your manual like stated above, i did that and learned a few things...now i just have to figure out if i have a Dana Spicer or Merritor set up.

Sorry JaggingBoomber, didn't mean for it to come out that way. Most of the time what I really want to say doesn't come out in my posts.

no problem...hey At least i went and got out that manual and did do some reading instead of just arguing my side. I always went by what the company told us about using the darn thing and it just didnt occur to me to read up on it since I very very rarely touch it anyway. Good info to have if you are in the snow alot.

Short Story
 

Last year when I got my CDL and not much experience with trucks, I was traying to leave my yard and the rear wheels started spinning in some mud, engaged the diferencial lock,got out and completelly forgot to unlock it until 400 miles later in Houston,Texas, nothing happened to the differentials

I hope I didn't ruin mine. Today when I picked up my trailer I had to use it in the snowy yard and then I drove 9 miles on dry pavement before I noticed that I left it on.

i know in my MACK with the diff. lock on a loud azz buzzer comes on and stays on intill you take the diff. lock off.

Power Dividers today are far and away superior to the power dividers of the 60's, 70's and early 80's. Technology ...go figure.

Now...the Wheel Differential Lock..that is sweet, if you are chained up, pulling 105,000 pounds, and climbing a mountain. It makes it tough though, if you have it engaged and try to turn a 90 degree corner. Lot's of crow hopping, even at slow crawl.

Yup you definitely don't want to have this thing engaged while it's slick out and you're going around corners. You greatly increase your odds of jacknifing under power.

It's the axle lock that you don't want to leave engaged. Most trucks nowadays will disengage the axle lock automatically at about 15 mph.

While this thread is going, may I ask this question? I drive a 2001 International 9200. On the lower left dash, next to the starter button, there is a toggle switch labeled "traction control" can someone tell me what it does, and when to use it? Thanks

All the traction controll usually does is reduce power if it detects slipping. My KW has an automatic ASR and it tends to piss me off but i guess it does its job.

Kind of an old thread, but good to bump.

I use inter axle quite a bit driving in Alaska. The idea is to get that last bit of traction so you don't spin out and have to throw chains. Where I use it most is locking in just before making a run at a long hill climb in winter conditions. I slow a bit to engage, then make my best run at the hill. Once cleared, unlock and go on my merry way. Inter axle is great for keeping speed for the climb and not getting so slow that engine torque breaks the tires loose.

Joe

Your's too eh?, did your Mack have it on the signal light too? That has to be the most annoying thing in the world.

Good bump for winter time.

Some of this varies by road and conditions...
 

If you're always (or most of the time) on pavement ALL of the above apply. If you're on slippery stuff, whether mud, sand, ice or snow the cautions about engaging while spinning are absolutely correct - you can blow up a differential by engaging any one of them with literally any difference in speed of the wheels. And, once you've engaged, as soon as you get back onto tractive surface you'd better disengage something.

However, at least in Alaska during the winter when there is a shoulder-to-shoulder sheet of ice or compacted snow, it's not unheard of to run at 55-65 300 miles and more with the Inter-Axle Lock engaged. It's also not that uncommon to drive with one Wheel Differential Lock engaged. Sometimes, during the worst of conditions, you can run for a few hundred miles with both the Inter-Axle and one (JUST ONE) Diff Lock.

A tandem-axle truck or tractor has One-Wheel-Drive - maybe the front, maybe the rear axle, but only one side of one axle. Usually the side with the least traction will start to spin causing loss of traction and forward motion. Engaging the Inter-Axle Lock will give you one wheel on EACH axle because it engages a gear that passes the power to each axle - that would give you Two-Wheels driving; again, one on each axle. Engaging the Diff Lock will give you Two-Wheel drive also, but only on one axle; both axles don't have power to them so only one will drive. Engaging the Inter-Axle Lock AND one Diff Lock will give you Three-Wheel drive; both axles, and both wheels on the 'locked' axle. It is also possible, with 'triple lockers,' to lock the Inter Axle and BOTH Diff Locks giving you Four-Wheel drive; both axles and both wheels on each axle. I've never seen a truck set up with Diff Locks on both axles but no Inter-Axle lock so I didn't discuss the possibility of both wheels on one axle driving and the other axle simply tagging along.

The remarks on understeer are very accurate and true. The Inter-Axle lock doesn't really affect your steering too much. However, with the Diff Lock engaged there is a tendency of the truck to run straight. The puny steer tires simply don't have the traction to overcome the tendency of the drive tires to go straight. And with BOTH Diff Locks engaged it's nearly impossible to turn the truck because all of the drive tires want to go straight and the puny steer tires don't have the traction to overcome them.

I can't emphasize two most important facts enough: NEVER engage any of the locks when there is a difference in wheel speed - NOT WHEN SPINNING, and; if everything is locked up (Inter-Axle and both Differentials) you're in a dangerous condition because steering is severely compromised. At any speed and/or for any distance this is simply deadly.

If there are any doubters next time you're stuck take a close look at which wheels ARE or ARE NOT turning/spinning. I've been stuck on glare ice on flat-level ground and had more than enough opportunities to observe this step-by-step. I've had all four drive wheels spinning - and everything locked up - and not been able to move but put a chain on a single tire and gotten moving. I've also had one wheel spinning and not been able to move. I chained it and the other wheel on the same axle started to spin. I locked the axle and got moving again. I've used the Diff lock and had one wheel on each axle spinning - chained one of the 'spinners' and had the other wheel on that axle spin along with the original spinner.

we have just got cummins and cat in New Zealand to put codes into our motors so when u push traction button it actualy disables it properly not how it used to be, rather keep going than derating

Periodically, the valve should be operated to make sure it moves freely; normally the valve should be kept in the unlock position.

THAT ALL GOOD MATE BUT WHEN YOU OFF ROAD TRACTION CONTROL LAST thing you want, you want all wheels going

Thank you Thompson Pass Trucker, this write-up is EXCELLENT and a must read for those who didn't know!

For those who haven't had the experience, having that one dual start spinning 3/4 of the way up a winter road is trouble! Very difficult to get it going again once stopped, assuming that you didn't already get it all crooked and into the ditch making the attempt before admitting defeat and chaining up.

The inter-axle also comes in handy in a bumpy yard, where you get a set of duals hanging in a depression spinning.

In the world of automated transmissions, spec'ing both an inter-axle and differential locks in fleet trucks are becoming more popular, as automated trucks have a bad habit of getting stuck in places a clutch would help ease you out. Like wet snow covered parking lots... lots of new drivers got yelled at in the beginning, but when your grizzled veterans start calling in stuck too...

Beware of the driving instructor/safety supervisor, with his ultimate authority, he easily falls into the trap of not checking his facts.
Who is going to challenge him? Pretty easy for him to say to the boss you didn't hear him right...

Drivers, protect yourselves, without verifiable sources and some written instructions, all that crap that was said out loud to us over the years must be viewed with suspicion.

Regardless of transmission, my bias in choosing a truck that will operate where there is the possibility of snow would be to have both inter-axle and differential locks available, and do some training with the drivers as to how easy it is to use them, and how easy it is to make the decisions as to engaging and disengaging.

I was reading the manual for my 2014 International sleeper this week. It mentioned using the inter-axle differential lock when backing under a trailer. That's a new one for me. Most of the times I have used it, I have used it when I was 90 degree backing up to a door over a surface that's got so much camber some of the wheels don't touch the pavement.

Instead of stopping to get it fixed, I was stupid and tried to make it home with one hell of a drive train vibration. I ended up dropping my rear driveshaft enroute. Using the interaxle lock saved me one hell of a tow bill! I could drive full normal speed, only problem was listening to that annoying beep all the way home.

Mackman: I had an early 90's Mack many years ago. Behind the interaxle lock switch was a spare wire harness that looked just like the one's on the interaxle, fifth wheel slide, and those switches. Unplug the plug from the interaxle switch, re-plug the spare one, and no more beep when activated.

I ran into a guy that broke a differential and he locked in the front axle and drove the truck several hundred miles to be repaired. He told me that since the rear differential was broken, it would pull against the front one. I talked to him on the radio, so you can take it with a grain of salt, but it seemed believable. I realize there are different types of interlocks, but I'm assuming this was some kind of front and rear together lock???

After reading Thompson Pass Trucker's description of how the Diff Lock and the Inter Lock works, I'm guessing the guy I mentioned used the Diff Lock only? I was told that all the power passed through the front diff and drove the truck off the rear unless locked in some configuration, which is why you would remove the front diff for a single axle usage except that the rear diff on a tandem is not exactly like the single axle diff, let's say on a Fed Ex truck with single. I'm guessing they use some sort of limited slip, otherwise those guys chaining up both sides were just wasting their time.......you could theoretically remove the drive shaft to the rear diff and lock the front diff and drive the truck in an emergency it seems. As to the opening post, I used to shift my 2001 Freightliner in and out of lock at highway speeds on snow all the time. I say highway speed, I never exceeded 45 mph because I was concerned about building heat in the differential for extended usage.