MAXI DRIVE Lockers?

[Puppa Sphinx]

Have a rover with MAXIs front and rear. Having problems with long delays when locking in and unlocking. Used to ARB Air lockers. Is there anything that can be done to improve the speed that they operate? / is this normal with the MAXI drive lockers?

[RangingRover]

Maxidrives only put the light on when they are actually engaged, unlike airlockers which turn the light on as soon as you push the button, although they may not actually be locked....

That said, maxis do take slightly longer to engage than airlockers, due to being vaccum operated. You could hook up an air compressor to operate the maxis, I believe, if you reverse the solenoid lines.....

[Slunnie]

Will the actuators handle compressed air?

[red90]

It has nothing to do with vacuum versus air....

It is just the algnment of the splines. You need to have some differential action to let the locking splines line up.

As stated, there is no way to "know" that an air locker is engaged. How are you deciding it is engaged?

[Hally]

I have maxi's front and rear and there is a trick to unlock the front diff lock . Just before you want to disengage the front diff lock turn the wheel from side to side at least one full turn each way and it should unlock quite easily as for the rear mine disengages with in 5 metres I have noticed the more I use them the easier they unlock they did take a while to unlock when i first used them

[Slunnie]

It has nothing to do with vacuum versus air....

It may have something to do with 100psi Vs manifold vacuum though, especially if there is pressure on the splines.

[ISUZUROVER]

It has nothing to do with vacuum versus air....

It may have something to do with 100psi Vs manifold vacuum though, especially if there is pressure on the splines.

Exactly. Manifold vacuum reaches a maximum of 15psi (or -15psi if you want to be pedantic) according to Mal. If you use more than 20psi you will bend the actuator.

I have no vacuum system on the IIA so I run my locker on 15psi compressed air. My rear locker locks and unlocks quite quickly (almost immediately). On hard surfaces (not that you need a locker) it may not lock straight away (if the splines aren't lined up) - but in these instances I just push the button back in and pull it out again and it usually locks.

What Rangingrover said above is the most important point, and ARB will light up as soon as you press the switch, a MD only lights up when fully engaged. Sometimes I can hear mine partially engage, and a second or so later there is another faint noise (more air passing through the switch to the cylinder) and the light comes on.

If your lockers are REALLY slow, it could mean a bent housing or bent axles, but this is unlikely.

[RangingRover]

but in these instances I just push the button back in and pull it out again and it usually locks.

Might have to try that one next time, instead of rocking the car backwards and forwards and swearing!

If you use more than 20psi you will bend the actuator.

That would mean that using air to operate them is fairly pointless then, I guess, unless you got the lockers without the vacuum capsule etc - and even if it wasn't, surely it couldn't make more than half a seconds difference in the time taken to slide the actuator over? Just out of curiosity, what pressure do air lockers run? Have never bothered to look too carefully into airlockers, I just like the Maxi setup.

[Slunnie]

AIrlockers are 85-105psi or similar

[ISUZUROVER]

That would mean that using air to operate them is fairly pointless then, I guess, unless you got the lockers without the vacuum capsule etc - and even if it wasn't, surely it couldn't make more than half a seconds difference in the time taken to slide the actuator over? Just out of curiosity, what pressure do air lockers run? Have never bothered to look too carefully into airlockers, I just like the Maxi setup.

Yes, using air doesn't make a difference, mine doesn't lock any faster than a vacuum operated one.

The reason ARBs lock and unlock faster, is that they have a mechanism similar to the way non synchro gearboxes engage (which of course needs to be fast too). However the high pressure is required to hold the locker on, and without it, it will unlock.

A guy in the club managed to lock his MD locker by sucking on the tube when he wanted to test the lockers before the install was finished. Try doing that with an ARB.

[bushy555]

It sux a little when your in water, the front line breaks, sucks in water, the o-ring in the switch fails and you've got water dripping out the switch behind the console.... And I aint gonna mention about all the drama's with water further up the line.

[Mark2]

Can anyone explain how the maxi vacuum system actually works?

I'm installing my second hand unit at the moment and am not sure how the brass actuator should work. Should it bleed vacuum off when changed from unlock to lock and vice versa? I'm assuming it does otherwise it would be fighting against the vaccum already in the cylnder.....
Does the maxi need vacuum to keep it locked? When I suck on the inlet, it seems to leak accross both red and green outlet ports when the knob is pushed in, but only one (the red one) when the knob is out. Is the valve faulty?
Thanks

[bushy555]

I'm installing my second hand unit at the moment and am not sure how the brass actuator should work. Should it bleed vacuum off when changed from unlock to lock and vice versa? I'm assuming it does otherwise it would be fighting against the vaccum already in the cylnder.....

Yep. exactly right.

Does the maxi need vacuum to keep it locked? When I suck on the inlet, it seems to leak accross both red and green outlet ports when the knob is pushed in, but only one (the red one) when the knob is out. Is the valve faulty?
Thanks

The actuator housing has a little ball bearing and spring inside which when locked does hold the actuator connecting rod in place if vacuum was lost.
It really only needs vacuum to engage and disengage, however having vacuum there all the time of course holds it in place.

As for the ports, the o-rings can be buggered or not in correctly both within the air fittings or within the switch itself. And just for the heck of it, check that you dont have something like metric in imperial and vice versa --- like 6mm air line in a 1/4" air fitting. Or 1/4" air line in a 6mm air fitting. It will sorta work, but there is enough difference to cause leaks around the o-rings inside the air fittings.

The o-rings inside the switch port and could also be buggered (is what happened to one of mine). The o-rings can easily be replaced - just need to disassemble to switch - need to knock out the little doovey-whats-it clips holding everything together. Fairly easy to do. Or buy a whole new switch for around $50.00 or so from the likes of Festo.
I must get around to fixing me front switch. Is leaking like buggery. You shouldn't be able to hear any leakage at all when idling or driving. And when you can hear it over the stereo doofing away, wind, turbo and road noise like I can, then you know you have a serious air leak. Heh!

[ISUZUROVER]

As mentioned above - vacuum is required both to lock and unlock.

The cylinder is sucked from one side to the other, and the other sides is vented to atmosphere.

If like me, you run the system on compressed air instead of vacuum, you need to swap the hoses over on the switch.

The switches are made by clippard minimatics in the US, are rebuildable, and new ones are readily available. A mate of mine uses one to work the CDL on his LT95, as they are much better than the standard switch.

[Mark2]

So does the venting occur through the brass valve/switch when its moved from one position to the other or at the cylnder? ie should there be any cross over between the outlet ports at the valve or is purely a diverter switch. Hope this makes sense........

[ISUZUROVER]

So does the venting occur through the brass valve/switch when its moved from one position to the other or at the cylnder? ie should there be any cross over between the outlet ports at the valve or is purely a diverter switch. Hope this makes sense........

If you look at the switch, (from memory) there is an inlet on one side, and 2 outlets on the other. There are also a couple of vents (the holes without threads). When the switch is in one position, the inlet will be connected to one of the outlets, ther other outlet will be connected to the vent. Vise versa when in the other position.

you can find diagrams here: http://www.clippard.com/store/byo_contr ... valves.asp

So the venting is at the switch. If working on vacuum that means you will be sucking air in every time you use the switch, so make sure it is somewhere where it will get clean air (like in the dash - not in the floor or seat box like I have seen some people do).

[Mark2]

OK - got it now - thanks