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MEXICOWANDERER's avatar
Mar 31, 2018

When You REALLY Don't Want A Bolt Or Nut Backing Off...



Ramp-Lock Lock Washers


The principle is simple
Tightening the fastener the washer halves go "click-click-click" as they revolve against one another.

Trying to back off the fastener, special hardened teeth on the underside of the washer bites into the parent metal. The complete washer does not spin.

The washer has to separate the washer halves.

Only there is a ramp on both sides of the washer faces.

And the ramp is of a much steeper angle than the nut or bolt thread angle. Where one turn of a washerless fastener may allow a fastener to rise 1/16" inch, the ramp lock washer has be forced 1/8".

In short, they do not back off accidentally, ever

And they need no heat like Loc Tite RED does to loosen

When I build an extremely high amp switch board this is what I use.

Or high amperage alternators. The through-case bolts.

14 Replies

  • The idea is very similar to what Audi/VW uses to bolt ring gears to differential carriers. I've NEVER seen them come loose if torqued properly. Audi/VW usually use fine (ISO 1.0mm) treads so a given torque gives more clamping force than the treads shown in your photos. They bite/lock really well especially on hardened materials.

    Chum lee
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Oh I don't know. Had to change a tire on an F-350 Custom 10,000 GVW straight truch, this has tires and lugs nearly as big as my RV (22.5, i Suspect it's 19's on the F-350)

    Using the standard Ford Truck lug wrench off the inner fender. I broke one lug and got the other 9 off no sweat. Put 'em back on and later when the corporate Tire Guy put his big Impact wrench on.. It was touch and go for they did not wish to come off.. I got 'em that tight

    Of course I was younger then.
  • There would be two parts, facing each other and THAT size you would need a five foot long 1" breaker bar. The # 10 size I use for alternator cases bends an Allan Wrench into an arc before it overcomes the ramp climb.

    SPIN LOC nuts have ribs but are not the same thing at all.


  • Looks like lug nuts on Ford vehicles. They have the same ribbed construction on the nut to rim surface.