Please tell me what this ‘cog’ is called!

[JasonBModerator @jasonb]

Can't you just get a billet of steel, drill holes round the edge and solder/weld/stick some metal pins into the holes. For the rack just drill holes in some square tube or use something like uni-strut.

J

[TerrydParticipant @terryd72465]

Hitsb,

Wot Jason said!!

T

[Ian PParticipant @ianp]

tsb

Another approach to getting a parallel motion would be to use a crossed cable arrangement as commonly seen on drawing boards and electric car windows.

All you need are grooved pulleys (four) and some Bowden cable. It does not require any real precision engineering, can keep the moving part perfectly tracked, runs silently, has no wearing parts so does not need lubricating, has little friction and no 'cogging'. Also it has an overall low weight in relation to its strength.

The 'peg in hole' example you linked to obviously works and if you were going to use that system I think you would need to use ready made metal sections that already had the series of holes (rather than drilling them yourself) and then experiment with the spacing and profile of the sprocket pegs.

Ian P

[BazyleParticipant @bazyle]

Bicycle chain and sprockets. Smaller chain is available. You can make chain sprockets by drilling a circle of holes and turning off the outside.

[jason udallParticipant @jasonudall57142]

If using chain..only need enough for through of machine … use cable and simple pulleys for return/tenion part….

but if pre perf section(thin wall for simpliciy) is available then the "tractor" would be good (until one holle stretches and thing squints)…

has got me wondering about "dexion" or din-rail .

Any way back to initil question…I think I would call the "cog", a sprocket…

been through wicksroyde , hpc And another whoes name illudes me but can't find one in a catalogh.

[Jeff DaymanParticipant @jeffdayman43397]

Ian – As I understand it this application is for a trailer to be used outdoors presumably summer and winter. Cables, especially ones exposed under a vehicle, have problems with thermal expansion hot to cold, corrosion, stretch and fatigue, so they are probably not best for this application, although theoretically they would work to do the job.

Bazyle – as a pretty large trailer was shown in the video as the application, bicycle chain and sprockets are likely too small for the job. The vertical play in the moving parts will likely need to be about the same depth of teeth in a bicycle sprocket, if the slide-out is to be capable of moving when hot/cold/filthy/wet/mud-covered/ ice-covered etc as can happen in trailers.

JD

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Use of chain is not confined to running it over sprockets or letting it hang loose . Chain will run well in square tubes which can be straight or moderately curved . Closed tubes for simple runs and open sided or slotted for taking a drive off .

Use of chain in tube mechanisms is commonplace in many low accuracy but very rugged applications ..

The cogged wheel that the original question is about doesn't have one particular name but in film and paper feed applications it is sometimes called a sync wheel .

Michael Williams .

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, a cog is a toothed wheel that will engage into a corresponding wheel or rack. Cogs don't generally engage into a chain or chain like mechanism.

The item that is being queried is without doubt a sprocket, whether it has a prefix name or not I don't know, that may be dependent on the manufacturers intended use, i.e. with one or two of the suggestions above it may well be known as a sync sprocket, or a traction sprocket etc.

Sprockets do not mesh or engage with other sprockets, they are usually driving a chain which in turn will drive another sprocket, however, in my previous employment there was a 20ft diameter suction drying table, driven by one sprocket which engaged into a continuous chain which was fixed onto a large tube that was part of the table. ( the chain and sprocket were several times larger than any bicycle chain and sprocket) It is not uncommen for spockets to drive flat plates with holes in them, as in shut off slides in powder, grain or any other granular management systems. It seems clear to me that the sprockets in the YouTube link, are engageing into holes in the box sections, it shouldn't be a to difficult task to achieve, as long as you can do the correct design or know someone else who can.

Regards Nick.

[TerrydParticipant @terryd72465]

Hi Nick,

just to be pedantic (as usual) but a cog is a single tooth. Cogwheels in flour mills etc used cogs around the rim of the wheel which could be replaced when worn.   So the device in question could correctly be called a cogwheel

Best regards.

Terry

Edited By Terryd on 31/10/2012 08:34:15

[Ian S CParticipant @iansc]

In many ways a chain is just an internal gear (OK its flexable). On a bit of agricultural machinery that we were at one time developing we needed a gear drive, so we welded a bit of chain on a disc, and used a sprocket as the other gear, worked well enough to prove that the idea for that machine did'nt work anyway. Ian S C

[Michael GilliganParticipant @michaelgilligan61133]

I have put a couple of pictures of that French HandDrill in an Album.

… Sorry about the shallow depth of field, but you should get the idea.

The Cogs are rounded to a bullet shape, and the mating side of the holes is countersunk. Ratio change is a simple matter of releasing the handwheel whilst sliding the cogwheel to a new position.

Pretty Nifty !!

MichaelG.

[Ian S CParticipant @iansc]

I remember that mum had a hand powered mixer/ beater (not sure what its called)in the kitchen, the large wheel, turned by the crank was made of two discs of steel with little hemispherical bumps around ech side of the rim, these drove two small wheels about 5/8" dia with dimples around the rim, giving two right angle drives to the rotating blades, no sharp teeth, unlike some older ones I seen. Ian S C

[Jeff DaymanParticipant @jeffdayman43397]

Semi OT off the thread topic, but…..

Hi Ian,

I remember a similar beater in our kitchen growing up, and later when I was working in a sheetmetal die shop, looking at this device again at home with appreciation of the skill that went into it. I remember thinking that it had several pieces that were the cleverest and best executed bits of sheetmetal die work I had ever seen. I remember the big crank wheel "gear" had the "teeth" formed from straps punched out of the disc's edge, one formed upward, one downward, from the disc sheet. Before plastics came on the scene for housewares, this type of high class metalwork was the state of the art, and remarkable in its own right. These products worked beautifully for many years and did not cost a fortune.

JD

[Author]

Posts