Our Reader's Write Back
Lockers Don’t Work Like That
In Lunchbox Lockers (Aug. ’12) you make three statements that are not true, or are misleading. First, you state on page 24, “Both brands of locker are automatic, which means they automatically lock when power is applied.” Having owned two Lock Rights, two No Slips, and one short-lived Detroit EZ-Locker, and having put many thousands of miles on them and learning how they work and behave while fully experimenting with them, I know this is not true. Application of power doesn’t lock them. In fact, whether under power, coasting, or decelerating, the half of the locker connected to the outside wheel disconnects, which causes the outside wheel to spin faster than the ring gear (allowing differentiation), while the inside wheel turns the same speed as the ring gear. The only time this doesn’t happen is if the driver applies enough throttle to cause the inside wheel to spin as fast as the outside wheel. Even when this happens (both wheels spinning the same speed), it isn’t really because the locker is “locked” per se, it is because of a loss of traction of the inside wheel (or both wheels) while the vehicle is turning, allowing both to spin the same speed. There are a lot of misconceptions about how a locker works, and the wrong description you gave contributes to the misconceptions.
Second, on page 27 you say, “Drop-in lockers require the use of an open differential carrier.” Although this is true for the Lock Right, it is not always true for the No Slip. There are No Slips made for limited-slip carriers.
And third, on page 26 you say, “No matter how extreme the terrain or twisted your suspension gets, each tire will continue to pull, even if one or all become airborne.” This is not true, because no tires pull if all become airborne.
William K. Halford
Thanks for the letter. You make some astute, if not entirely accurate, observations. First, the functioning of any automatic locker is for the outside wheel to overrun its clutches to disengage, which it will if it is going faster than the ring gear. But under power they both must turn at the same speed. As you wrote yourself, “if the driver applies enough throttle . . . ” hence under power. Not enough throttle is indeed not enough power to lock the locker, and when it does, that is what causes that slippery feeling on a slope or ice—both tires are spinning since the locker is locked.
A locked locker doesn’t necessarily equate to traction; it can be quite the opposite. Different rolling radiuses of the tires on the axle can also cause unequal locking characteristics. The locking mechanisms are simple, overriding dog clutch teeth—there is no magic inside, simply real mechanical physics.
Finally, nice catch! Yes, our sentence was poorly written in that respect, but what if the air was thick and the rig had monster fan-blade paddle tires? Oh well, thanks again for writing.
In your new series called Tool Shed [“Mighty Fine Mat,” July ’12], I believe you meant to state that the mat comes in 0.75mm or stiffer 0.95mm thicknesses, not “75mm” or “95mm” (which would be 3 or almost 4 inches thick!) I’m sure I’m not the only person who caught this. Thank you anyway for a cool tech product update.
The thicknesses were actually 75 and 95 mils (0.075 and 0.095 inch), but the term got changed to mm by mistake. It’s a great mat, but not as thick as a 2x4. Sorry for the typo, and thanks for pointing it out.
Forward Controls Rule
Great article on the FC concept [“Will We See It?” sidebar in “The Mighty FC,” Aug. ’12]. I agree that using the Iveco 4x4 as a starting point would be a great way to return the FC to the Jeep fold. No problem here with using the chassis—platform sharing is commonplace between makes. Only problem I see would be choosing to make the truck either a midsize or an HD. Midsize would appeal to casual use, HD would appeal to landscapers, utilities, etc. Snowplow companies would greatly benefit from the improved visibility from the FC setup. The diesel engine would be a must for this truck either way—looks and pedigree would only take you so far. Need a solid anchor to pull in the buyers who cannot make up their minds. BTW, great shot of Fred’s FC in the background! Especially cool how the colors match.
We love FCs and look for them everywhere we go. This is a pair found in the hills of Washington, patiently waiting to be brought back to life by their owner.