What's the diff? Roothy's Milo gets a flash upgrade
Roothy's been banging on a fair amount about his new ELockers and how they're the best thing since Betty White (seriously, she's older than sliced bread, look it up).
He likes them so much he asked me to put together an article covering the ELockers getting installed into Milo.
The industry standard here would be a half-cobbled-together tech piece covering the install.
But the truth is you're not learning everything you need to know about ripping your diff down to its last nuts and bolts in a single article, and we like to do things a little differently here at LowRange.
So I figured instead I'd focus on the why, rather than the how.
Now Roothy tends to get a little bit excited when he comes across a bit of gear he likes, which is pretty understandable. When you've been in the industry as long as him most gear just starts to blend into the background after a while.
Because of that I'm going to go into a bit of detail here on what lockers are, how they work, and why Roothy is jumping out of his skin to tell everyone who looks at him sideways about his new ELockers.
WHAT'S THE POINT OF A DIFF LOCK
The whole idea of a diff, and where the term differential came from, is their ability to differentiate speeds. As you turn a corner the outside wheel needs to go a hell of a lot faster than the inside. A regular open diff does this by sending power to the wheel with the least resistance, letting the other wheel fall behind.
The problem with this is as soon as a wheel loses traction, either through lifting into the air or losing grip with the terrain, all the power gets sent to it, not to the wheel that still has traction. Not ideal.
As most 4WDs have open diffs from the factory you've only ever really got 2WD at best, kick that back to one wheel drive if you lift a wheel. You can see how that'd be pretty average with the kind of terrain Roothy and the boys take on in the DVDs. The solution of course is a Diff Lock.
What they do is physically lock the two axles together sending equal drive to both, no matter which one has traction. That means as long as you've got a tyre with grip you've got forward momentum; well that's the theory anyway.
HOW DO THEY DO WHAT THEY DO?
Inside the diff centre there's a set of gears known as the pinion gears and side gears (connected to the axles and then the wheels). As drive is sent into the diff through the driveshaft the pinion gears spin with the crown wheel and push on the two side gears. Whichever side has the least resistance (traction) gets drive sent to it, while the other side is able to stop completely.
The basic idea behind any locker is to stop the pinion gears from doing what they're designed too, allowing one wheel to fall behind.
There's a couple of ways manufacturers can achieve this, some with less success than others.
The cheapest (and weakest) is a lunchbox locker, which replaces just the internal gears inside the carrier leaving the factory cast gear carrier in place. There's not a great deal of room inside the factory carrier so the locking mechanism is generally small, and as a result, weak.
Full carrier lockers like the ELocker completely redesign the centre and integrate the locking mechanism into it by physically locking one of the side gears into the pinion gears at the flick of a switch, forcing both axles to spin at the same speed. It's a stronger, smoother system with less to go wrong.
WHAT'S SO GOOD ABOUT ELOCKERS?
As mentioned earlier there's a few different style of lockers that all perform very differently. Auto lockers will engage and disengage themselves without your input, while spools are fully locked 100% of the time. For everything else you need some way to engage and disengage the lockers, and this is where ELockers excel (there's a reason Roothy won't stop raving about them).
Some of the earliest systems used a physical cable, so in the cab you'd have a couple of levers that'd operate like a bonnet release cable all the way down to the diff. The problem with this is they're clunky, uncoordinated, and damn hard to engage and disengage on the fly. Imagine trying to turn your windscreen wipers on halfway up a rocky hill climb.
Air or vacuum lockers basically revolutionised diff locks making them more like a factory feature rather than an agricultural implement. They both work in effectively the same way, instead of a cable engaging the gears they're engaged from air pressure (either positive or negative).
The downside to this system is they're complicated with valves, air lines and compressors, and complicated means potential failures.
By ditching the air-lockers in Milo and slotting in the ELockers Roothy has cut the potential failure points down massively. Instead of the switch on the dash operating a complicated air system it now sends power directly into the diff lock itself. No connections, no other components, no worries.
So there you have it, the first why instead of how DIY. Clear as mud?