Reply
Thread Tools Display Modes
#1
Old 11-06-2001, 07:09 PM
BANNED
Join Date: Jan 2000
Location: Buford, Georgia
Posts: 8,011
Reduced friction? Torque absorbsion? Strong-arm washerwrights' union? Don't laugh - I bet a lot of us don't know.

(In what promises to be a series of threads "questions my daughter asks that I can't answer")
#2
Old 11-06-2001, 07:13 PM
Charter Member
Join Date: Sep 2000
Location: Northern Idaho
Posts: 1,374
Regular washers don't keep nuts and bolts tight. Lock washers however do and they have small raised ridges on one or both sides to help adhere to the material being bolted.
#3
Old 11-06-2001, 07:14 PM
Charter Member
Join Date: Jan 2000
Location: NoWA
Posts: 57,960
I'm not sure that washers themselves keep nuts tight on the bolts. I think a lock washer exerts an additional force on the threads, creating more friction.

But I'm not a mechanic.
#4
Old 11-06-2001, 07:17 PM
Registered User
Join Date: Mar 2000
Location: Washington dc
Posts: 16,441
Well, there are washers and then there are washers. For example, Maytag makes some mighty fine washers... oh? that's not what you meant? ok... ahem

There are washers and there are washers. a flat washer is meant mainly to spread the load, not to prevent the nut from coming loose. A locking washer designed to prevent the nut from coming loose works by increasing friction. This is generally accomplished by teeth or grooves that cut into the metal, by use of plastic or rubber or by other means.
#5
Old 11-06-2001, 07:19 PM
Member
Join Date: Nov 1999
Location: Phoenix, AZ, US
Posts: 7,672
For big solid things like engine blocks and wheel hubs a bolt can be tightened enough to stretch it slightly but not permanently. This keeps the threads under pressure so they are less likely to slip and loosen. When a bolt can't be stretched much a split or star lock washer can accomplish the same purpose. The split and star segments also dig into the mating surface of the nut slightly to keep it from moving.
#6
Old 11-06-2001, 08:41 PM
Guest
Join Date: Mar 2001
Posts: 1,631
There are also things like castellated nuts, which have a jagged edge on the back. You put a castellated nut on a special bolt which has a tiny hole drilled laterally through its shaft (ouch!). Then a lock wire is inserted through the hole and engages the nut. There's no way that's coming off unless the wire breaks.

You can also use stuff like "Loc-Tite" or some other liquid thread locking compound.

But washers to keep nuts and bolts tight? Naaah. That's sissy stuff.
#7
Old 11-06-2001, 09:10 PM
Guest
Join Date: Mar 2001
Location: Somewhere cold 'n squishy
Posts: 5,196
Seconding what Padeye said...

Bolts 'n screws stay tight because of the slight elasticity of the metal, or of the material that they have been screwed into. The shaft and threads stretch slightly which greatly increases the frictional force retaining the threads in place. The washer itself provides a uniform surface to distribute the load across whatever you have screwed into, but doesn't affect the tightness or retention of the bolt directly.
#8
Old 11-06-2001, 11:08 PM
Guest
Join Date: Jun 2001
Location: Los Angeles, CA
Posts: 232
Aside from lock washers, there is another class of washers designed specifically to maintain tightness (preload) in bolted connections called Spring Washers. They’re used because bolted joints can loosen up over time due to relaxation of the bolts, gasket creep, vibration, and thermal transients.
#9
Old 11-07-2001, 01:30 AM
Guest
Join Date: Nov 2000
Location: Chicago
Posts: 166
Sorry if this one was mentioned already, but this thread is driving ME NuTS TOO!!

There are washers that are split in one spot from center to outer edge (making a break in the circle). One edge (or end) is bent one way, and the other edge is bent the other way.

As it is smashed between said Nut n Bolt, it acts as a spring & exerts outward pressure creating increased friction, I believe. IT'S NUTS!!!
__________________
Knowing the difference between cleverness and simplicity is the beginning of wisdom.
#10
Old 11-07-2001, 02:29 AM
Charter Member
Join Date: Aug 1999
Location: Bubbaville
Posts: 4,726
Split washer locknuts are not springs; they're made out of about the same grade of steel as the nut and bolt, not spring steel. Split washers are usually put between a nut and a flat washer and work by digging into the faces of the nut and flat washer which keeps them from turning.

The Book, more than you wanted to know...
#11
Old 11-07-2001, 11:24 AM
Member
Join Date: Nov 1999
Location: Phoenix, AZ, US
Posts: 7,672
Quote:
Originally posted by cornflakes
Split washer locknuts are not springs;
Sure they are. Pressing a lockwasher flat doesn't exceed its elastic limit in most cases so it's providing extra pressure to the edges digging in and springs back to shape when the nut is removed.
#12
Old 11-07-2001, 01:04 PM
Member
Join Date: Mar 2000
Posts: 8,117
In some high load applications where there is a large force to counter or contain, rather than just holding bits of metal together, the bolts are pre-stressed.

These are first measured accurately for length and are then tightened to achieve a certain stretch length.
Thes types of fastening are sometimes called fitted or machine bolts, you see them in places such as large conrods, or high compression cylinder heads on very large diesels(no not truck engines I mean LARGE engines)
#13
Old 11-07-2001, 01:28 PM
Charter Member
Join Date: Aug 1999
Location: Bubbaville
Posts: 4,726
Quote:
Originally posted by cornflakes
Split washer locknuts are not springs.... (They) work by digging into the faces of the nut and flat washer which keeps them from turning.
Uh, (how should I put this), after checking the very book that I offered as a reference, I'll have to admit that I was wrong on this one. Sorry, people...
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 09:06 AM.

Copyright © 2017
Best Topics: funny check memos picking people up firefighter weed vhs porn indian nuts sleping gas ww1 paratroopers gas fireplace scent hopless beer caius pronunciation wireless coax transmitter peeing calvin shoes fly off alcohol listerine lynn ricart adderall cost walmart reddit double penetration canadian tire usa cici deville chicken feet tongs joes stuff oxygen bar high flaps under tongue ggf meaning target butane refill forty winks meaning pinot noir chill san jose suburb sofa king jokes outback curbside halliburton address edna babish yours etc electric prostate stimulation wen tools review dragon skin body armor prices cell phone time is wrong can you eat expired popcorn kernels sawed off shotgun illegal calories in confectioners sugar send a song from itunes why do people get tongue piercings at what distance should headlights be dimmed to oncoming traffic why do some people capitalize every word how to join the pipefitters union ge potscrubber won't drain did margaret avery sing in the color purple there once was a hermit named dave yours is no disgrace lyrics meaning the path of the righteous man is beset on all sides price of official nfl football if someone breaks into my house can i shoot them chain link fence scrap value how to tie a rope around a ball volvo 240 heater fan replacement mr bean theme song how to say youre welcome in japanese are vocational schools worth it hotel with no credit card how hard is it to learn java does things remembered engrave outside items bluetooth cell phone external ringer you are getting sleepy very sleepy what is the difference between a detective and an investigator does spicy food cause diarrhea what did the natives call america jury of peers definition one of if not the best macallan select oak 1824