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The Test

With the testing rig complete, we inserted the AutoWrench into the lever arm and motored the wrench’s jaws closed on the test tubing.  We attached the spring scale, started the camera, and pulled.



In the first test, the autoWrench gave way at a measured pull of 72 lbs, which with a 3′ lever arm represents 216 ft-lbs of torque.  Considering that our scale measures in 2 lb increment — leaving us with a resolution of 6 lbs — that’s close enough to validate Black & Decker’s claim of 225 ft-lbs.

Then we tried the test four more times, resulting in 26 lbs (78 ft-lbs), 12 lbs (36 ft-lb), and 18 lbs (54 ft-lbs) respectively, revealing an interesting fact about the AutoWrench: Once you’ve exceeded its maximum torque capability, the wrench is damaged and loses most of that capability.

To obtain some baseline comparison data, we tried the same test with a cheap Chinese-made standard adjustable wrench, measuring to assure the lever arm was inserted at the correct length.  Unfortunately, we reached the limits of our test rig before we were able to break it.  Even though we counter-twisted with a 10′ piece of 2′ square tube to steady the anvil, it started to move as we approached the 100 lb pull mark.  We were able to apply a maximum of 98 lbs — 294 ft-lbs of torque — before the rig slipped.  The wrench was undamaged after the test.




In fact, as we approached the 300 ft-lb mark — about 3 times the torque you’d apply to the lug nuts on your car — we actually began to deform our lever arm.  If we try this type of test again, we’ll probably have to add some additional steel structural support.

post-aw25.jpg  post-aw26.jpg  post-aw27.jpg

Failure Mode

At first we thought the AutoWrench was broken, but whacking it on the anvil to un-stick the screw mechanism rendered it operable again — at least in terms of the motorized screw.  Upon closer examination it became clear that when the wrench failed, it simply flexed enough to allow the “pinion” screw gear to jump over one or more notches in the fixed “rack.”

post-aw22.jpg  post-aw23.jpg  post-aw24.jpg

We suspect Black & Decker designed in this behavior as it allows the wrench to behave in a much safer fashion under extreme loads.  Upon failure, the AutoWrench simply clicks open a bit rather than breaking apart. 

On page 4: After a reality check we take the AutoWrench apart.

pages: 1 2 3 4


29 Responses to Hands-On: Black & Decker’s AutoWrench

  1. Fletcher says:

    Excellent write-up!

  2. Sean says:

    Great review, I love that last line 🙂

  3. Kubik says:

    I bought this a couple of months ago on it’s “coolness” factor after playing with it on the endcap display. Have yet to get any regular use out of it, but it’s good to know the quality is there and that it’s not junk. Thanks, Toolmonger!

  4. Rob says:

    I really don’t understand the need for this tool other than to sell more batteries. Is it really that hard for people to operate an adjustable wrench with one hand?

    Nice writeup guys, it’s good to know that this tool will perform if one should ever end up in my tool box

  5. Rob says:

    I really don’t understand why this post is longer than 5 paragraphs. Did it work? That’s all I want to know. I don’t care what color shirt you wore that day.

  6. Jason says:

    “I really don’t understand why this post is longer than 5 paragraphs. Did it work? That’s all I want to know.”

    Eh, I don’t know. I assume you’re referring to the extended coverage of the torque test. Well, the tool claimed a specific torque specification and the review put that claim to the test. I, for one, appreciate that they explained their testing methodology.

    Maybe you could suggest something like “hey, could you implement a star system for the tools you review,” or “hey, could you give a quick verdict at the top of the review for people who like to skim?”

  7. John says:

    Very nice review. I loved the depth of detail that you went into on how you did your torque tests. Thanks for adding the baseline info. So the motor is like the kind you would find in a toy car, or is there some sort of gear head on it.

  8. Derek Hunt says:

    Reviews need to be indepth (good write up BTW).

  9. Chuck Cage says:

    It’s exactly the kind you’d find in a toy car. There’s a small plastic pully on the end that drives the screw via a belt. The rocker switch is also mounted on a small (just barely bigger than the switch) board that’s easily removable. In fact, you can pull the whole mess out without cutting the wires.

  10. Kyle says:

    “I really don’t understand the need for this tool other than to sell more batteries. Is it really that hard for people to operate an adjustable wrench with one hand?”

    I never knew this product existed, but after reading this I might have to go out and buy one. This would be an invaluable tool for someone working with very tight clearences, such as under a car. You have no idea how handy this would have been on the last couple projects I did; removing driveshaft bolts without dropping the exhaust of a rear-wheel drive car for instance. It’s a handy little gadget that just might wind up in my toolbox!

  11. Rob says:

    “This would be an invaluable tool for someone working with very tight clearences, such as under a car.”

    But really, shouldn’t you have the correct size combination wrench for that? I use an adjustable when I’m in a rush but I’d rather not risk rounding a nut on my car.

  12. Mike says:

    I think this thing would be good for one of those road side assitant kits that you put together and leave in the back of you car. Or for leaving in the stuff drawer in the kitchen.
    Because as we all know. Use the right tool for the right job. An ajustable wrench isn’t the right too for anything.

  13. Dale says:

    This looks like the type of tool that would be pretty handy to have in the kitchen drawer. Under a car doesn’t sound like a good place for this wrench unless the inner workings are very well sealed.

    Based on the description of the motorized adjusting system, I suspect that a slug of just about any fluid that would come out of a car could render the tool non-functional. Likewise bits of rust and gunk that tend to break loose from a nut or bolt being tightened or loosened could jam things up.

    The tool certainly seems to have lived up to it’s claims and expected functionality, but I can’t imagine me buying one.

    Nice writeup.

  14. Jeff says:

    Cool write up — looks like you had fun testing it. I don’t use adjustable wrenches much, so I can’t see spending $30 on a novelty tool. It seems like a product in search of a market.

    Found you via MAKE Blog.

  15. John says:

    Great write up! I got a question for you. The picture that shows the wrench that you compared the Autowrench to looks like you used a 10″ adjustable. If this is correct than a 10″ adjustable is normally rated at higher foot-lbs. torque and of course would out-beat an 8″ adjustable like the Autowrench. However, it sounds like your test confirmed that the Autowrench is a quality tool and is a new twist for an old tool! Thanks again for an indepth report.

  16. Michael Cole says:

    Did you actually know the reason for the length of the spanners. Ever seen a 10mm spanner with a really long handle.

    From what i heard is that the length is based on the torque that should be placed on to a bolt.

    A longer handle will place too much torque on the bolts.

    Try always to use the correct spanner for the job so you will not destroy the bolts. If you need specific torque for a bolt there are some good small, medium and large Torque spanners or attachments for your tolls available.

    For safety never add an extender to a spanner unless it is designed as such.

  17. Eugene says:

    Good test, I guess. It worked well around the shop, but let’s see if we can break it. Okay. Wouldn’t a more fair comparison, though, have been to have tried the same leverage on Cooper Tools, Crescent Wrench that has a manual slide to adust the wrench, instead of a standard adjustable wrench?

  18. Wendy says:

    Awesome review! Very informative! It sounds like the perfect gift for the man who already has everything…my dad. Thank you!

  19. Jeff says:

    This is the most in-depth tool testing I’ve seen published on the internet. Neat examples using sound principles by folks that obviously know their stuff (plus who doesn’t love using a plasma cutter). Keep up the nice work, people!! More and more tool shoppers will visit your site with a little “word of mouth” advertising, and I plan to begin just that.

  20. Don says:

    I saw this tool years ago on a Modern Marvels inventor’s show. My question is:
    Did the inventor sell this to Black and Decker, or did they steal his idea? Anyone who knows can email me at Dpehta@aol.com. thanks!

  21. JP says:

    Don, I am happy to say that Black & Decker is an honorable company and they did not steal my idea. We signed last year and we worked together to bring the latest and greatest to the people. Black & Decker has done an outstanding job on the “Auto Wrench” and I am very happy to be with them. Merry Christmas and Happy New year to all.

    The Inventor

    (P.S.) Now if we can only get Modern Marvels to do a sequel we could share the rest of the story and good will to all!

    BTW- These guys here at Toolmonger did a good job, too.

  22. eddie says:

    my cogged belt broke and the replacement is not available from the b & d site. never actually used the tool, only played with it

  23. Leslie says:

    Old post but considering the recent comment I’ll add:
    Good review and I enjoyed reading the testing process.
    And this has been a great tool to get as a “what in the WORLD do I get him/her” gift for anyone at all into gadgets. I can’t at all say if they used it (especially, as others have mentioned, how often do we really need an adjustable wrench??) or how well it worked, but the smiles over it’s “coolness” factor were worth the cost.

    And definitely get one from the BACK of the rack, if you want the batteries to have any life to them.

  24. Bill Mackey says:

    I have had this wrench for a while. I used it once or twice, but most recently it failed due to the belt breaking. It would be easy to replace, but I can’t find it anywhere. Anybody got any ideas?

  25. Wally Larsen says:

    I got this a couple of years ago as a present. I just took it out of the package and found it would not work. After replacing the batteries, I discovered that the cheap plastic drive belt was broken and no replacement parts are available. What a piece of junk! A sizable investment worthless for a 2 cent part.

  26. TPS says:

    The rubber belt brakes and can’t get a replacement belt. I don’t recommend this product.

  27. David says:

    Does anybody know how to remove the pin that holds the gear for the belt to the motor for the b&d aaw100

  28. glen says:

    i also want to know how to replace the belt

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