Lockers
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Joined: Feb 2003
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From: North Georgia
Lockers
I want to get lockers or a limited slip diff, but I need more info.
Where can I learn more about these. I found a article that explained how the two worked and named Detroit Tru trak I think. But I can't find it again.
Please Help
Where can I learn more about these. I found a article that explained how the two worked and named Detroit Tru trak I think. But I can't find it again.
Please Help
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Lockers
Copied from another BBS - originally posted by me:
An automotive differential is a mechanism for dividing the engine's power between 2 shafts, most often between the 2 axleshafts within an axle. It involves a "carrier" which contains 4 bevel gears; 2 facing each other on a shaft perpendicular to the carrier's axis (spider gears), and 1 on each axleshaft concentric with the carrier's rotation (side gears). When the vehicle is rolling straight, the spider gears don't rotate on the pinion shaft, but merely convey power from the carrier (which is driven by the ring & pinion gears) to the axle gears which ultimately turn the tires. During a turn, the spider gears spin (opposite each other) to allow one axle to turn faster than the other. The problem is that the spider gears can spin fast enough to allow ALL the power to go to ONE axleshaft, leaving the other NOT TURNING AT ALL. This is an "open" differential and is used on almost all production vehicles; front, rear, or all-wheel drive. Some 4WD vehicles are manufactured with open diffs.
The easiest solution to the wheelspin allowed by an open diff is to eliminate all differentiation by either replacing the carrier & its contents with a solid piece of metal called a "spool", or by making the carrier & its contents solid by welding everything together (a "Lincoln Locker" named for the brand of welding machine), or by replacing only the contents of the carrier with a "mini-spool". But this produces unpredictable behavior on-road.
A better solution is to limit how fast the spider gears can turn by braking the axle gears - "limited slip". This involves simple springs pushing on friction materials inside the carrier, but sometimes requires additives to the oil. They also wear constantly, so they require service to continue to function. Also, they can be easily overwhelmed by wear, engine power, or driveline torque (big tires or a heavy vehicle). Some brands of LSD's are Ford's Trac-Loc, GM's Positraction, Dana's HydraLok, and Auburn, and each uses a specific carrier different from the open diff's.
An even better solution is "torque biasing" in which a mechanism varies the braking effect to send the torque to the tire with traction. This type uses even more unusual carriers. GM's Gov-Lock uses an extremely complex & delicate arrangement of clock springs, counterweights, and clutches to do an effective job. The TracTech True-Trac uses a much simpler, more robust, & more elegant arrangement of helical gears, but still suffers from wear. Zexel's TorSen claims not to suffer from wear, but is only available for the Ford 8.8", the Ford 9", the GM 8.5" (10 bolt ), and the GM 7.5".
A solution that virtually eliminates wear is the TracTech Detroit Locker, which uses toothed rings held in engagement by heavy springs to transmit power from the ring gear to the axleshafts. They replace the stock carrier, but require no modification to the axle housing. There is no differentiation (in the pure sense) since they act as a spool, but the differential effect is still achieved when the rings disengage under extreme driveline torque, momentarily allowing one axle to freewheel to relieve the torque. There are many copies of this design marketed under many names, and there are also "mini" versions which replace only the contents of the carrier but are considered far weaker. Here's a step-by-step install of a mini-locker. While VERY dependable (except minis) & effective, these show the same unpredictability as a spool when driven on ice. Some also produce an audible popping during normal on-road operation.
The type that started this thread is the "selectable locker" which gives the driver direct & immediate control to change from an open diff to a spool. A few older 4WD's came with this feature, but now it is only available from the aftermarket. ARB sells the most popular which uses an air diaphragm in a proprietary carrier to apply force to the clutches that lock the diff. While effective & convenient, it is expensive to buy, expensive to install, and requires an on-board air source which is also expensive. It requires some drilling of the axle housing for the air line to be routed thru, and some owners have found air leaks to be a problem. The Eaton E-Locker promises simplicity over the ARB since it uses electromagnets to lock the diff, but the price has not yet been published and they have no history to judge their quality.
This is an excellent illustrated & animated tutorial on the functioning of differentials, and the rest of the web site is a WEALTH of information & links.
This is another article comparing types of diffs.
***********************************
Some of those links may not still be active, but most of them should be.
An automotive differential is a mechanism for dividing the engine's power between 2 shafts, most often between the 2 axleshafts within an axle. It involves a "carrier" which contains 4 bevel gears; 2 facing each other on a shaft perpendicular to the carrier's axis (spider gears), and 1 on each axleshaft concentric with the carrier's rotation (side gears). When the vehicle is rolling straight, the spider gears don't rotate on the pinion shaft, but merely convey power from the carrier (which is driven by the ring & pinion gears) to the axle gears which ultimately turn the tires. During a turn, the spider gears spin (opposite each other) to allow one axle to turn faster than the other. The problem is that the spider gears can spin fast enough to allow ALL the power to go to ONE axleshaft, leaving the other NOT TURNING AT ALL. This is an "open" differential and is used on almost all production vehicles; front, rear, or all-wheel drive. Some 4WD vehicles are manufactured with open diffs.
The easiest solution to the wheelspin allowed by an open diff is to eliminate all differentiation by either replacing the carrier & its contents with a solid piece of metal called a "spool", or by making the carrier & its contents solid by welding everything together (a "Lincoln Locker" named for the brand of welding machine), or by replacing only the contents of the carrier with a "mini-spool". But this produces unpredictable behavior on-road.
A better solution is to limit how fast the spider gears can turn by braking the axle gears - "limited slip". This involves simple springs pushing on friction materials inside the carrier, but sometimes requires additives to the oil. They also wear constantly, so they require service to continue to function. Also, they can be easily overwhelmed by wear, engine power, or driveline torque (big tires or a heavy vehicle). Some brands of LSD's are Ford's Trac-Loc, GM's Positraction, Dana's HydraLok, and Auburn, and each uses a specific carrier different from the open diff's.
An even better solution is "torque biasing" in which a mechanism varies the braking effect to send the torque to the tire with traction. This type uses even more unusual carriers. GM's Gov-Lock uses an extremely complex & delicate arrangement of clock springs, counterweights, and clutches to do an effective job. The TracTech True-Trac uses a much simpler, more robust, & more elegant arrangement of helical gears, but still suffers from wear. Zexel's TorSen claims not to suffer from wear, but is only available for the Ford 8.8", the Ford 9", the GM 8.5" (10 bolt ), and the GM 7.5".
A solution that virtually eliminates wear is the TracTech Detroit Locker, which uses toothed rings held in engagement by heavy springs to transmit power from the ring gear to the axleshafts. They replace the stock carrier, but require no modification to the axle housing. There is no differentiation (in the pure sense) since they act as a spool, but the differential effect is still achieved when the rings disengage under extreme driveline torque, momentarily allowing one axle to freewheel to relieve the torque. There are many copies of this design marketed under many names, and there are also "mini" versions which replace only the contents of the carrier but are considered far weaker. Here's a step-by-step install of a mini-locker. While VERY dependable (except minis) & effective, these show the same unpredictability as a spool when driven on ice. Some also produce an audible popping during normal on-road operation.
The type that started this thread is the "selectable locker" which gives the driver direct & immediate control to change from an open diff to a spool. A few older 4WD's came with this feature, but now it is only available from the aftermarket. ARB sells the most popular which uses an air diaphragm in a proprietary carrier to apply force to the clutches that lock the diff. While effective & convenient, it is expensive to buy, expensive to install, and requires an on-board air source which is also expensive. It requires some drilling of the axle housing for the air line to be routed thru, and some owners have found air leaks to be a problem. The Eaton E-Locker promises simplicity over the ARB since it uses electromagnets to lock the diff, but the price has not yet been published and they have no history to judge their quality.
This is an excellent illustrated & animated tutorial on the functioning of differentials, and the rest of the web site is a WEALTH of information & links.
This is another article comparing types of diffs.
***********************************
Some of those links may not still be active, but most of them should be.
Last edited by steve83; Feb 23, 2003 at 11:06 PM.
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