Author Topic: Tappets  (Read 1079 times)

Offline duTch

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Tappets
« on: 23.09. 2015 09:11 »

 Hi guys, as this is relevant at the moment, regarding the term "Tappet"...; For a long time, I've regarded a tappet to be not a physical item as is often used to describe various bits in the valve train such as; cam followers/lifters, valve lash adjusters/tappet adjusters, valve clearance adjusters.... but just to maintain some conformity/uniformity (a concept that doesn't come to me easy, believe me), I was told at a young age that a 'tappet' is a gap/space/ somewhere there is nothing but nothing...but a space >< that can be adjusted if need be... *fight* *beer*
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Online Greybeard

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Re: Tappets
« Reply #1 on: 23.09. 2015 09:28 »
I believe the tappet is the cam follower.

Offline kiwipom

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Re: Tappets
« Reply #2 on: 23.09. 2015 10:23 »
Hi GB, when you adjust the 'Tappets' you do not adjust the Cam Followers, the Tappet  is the bit you adjust, cheers
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Re: Tappets
« Reply #3 on: 23.09. 2015 10:33 »
Hi GB, when you adjust the 'Tappets' you do not adjust the Cam Followers, the Tappet  is the bit you adjust, cheers
https://en.wikipedia.org/wiki/Tappet#/media/File:Pushrod2.PNG

Online bsa-bill

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Re: Tappets
« Reply #4 on: 23.09. 2015 10:46 »
a few definitions of Tappet non are specific to any one part of the mechanism to move a valve up and down but rather apply to any one of the parts involved ( does that make any sense).
The nearest the most specific is
Quote
A lever or projecting arm that moves or is moved by contact with another part, usually to transmit motion, as between a driving mechanism and a valve.

Also
 
Quote
The term tappet is widely used in relation to internal combustion engines, but imprecisely. It is most commonly encountered as a maintenance task for overhead valve engines, that of 'adjusting the tappets'. This operation adjusts the overall clearance in the valve actuation system: typically 20 thousandths of an inch (0.5 mm). The name arises because it is the clearance of the tappets that is being adjusted, even though the adjustment is not made to the tappets themselves.

And historically
Quote
The term is first recorded as part of the valve gear of Thomas Newcomen's atmospheric beam engine, a precursor to the steam engine. The first Newcomen engines had manually worked valves, but within a few years, by 1715, this repetitive task had been automated. The beam of the engine had a vertical 'plug rod' hung from it, alongside the cylinder. Adjustable blocks or 'tappets' were attached to this rod and as the beam moved up and down, the tappets pressed against long levers or 'horns' attached to the engine's valves, working the cycle of steam and injection water valves to operate the engine.[1] This operation by tappets on a plug rod continued into the early twentieth century with the Cornish engine.[2]
All the best - Bill
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Offline duTch

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Re: Tappets
« Reply #5 on: 23.09. 2015 11:25 »
 
 Ok, in all fairness, I was just looking up the pushrod part #'s and  just down are #'s 67-0332/67-0333 (A7/10/S.T. -Tappets), but-but...what I already said; it gets a bit confusing at times
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

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Re: Tappets
« Reply #6 on: 23.09. 2015 11:56 »
Ok, in all fairness, I was just looking up the pushrod part #'s and  just down are #'s 67-0332/67-0333 (A7/10/S.T. -Tappets), but-but...what I already said; it gets a bit confusing at times

Now look what you've started; a tappet war!  ;)

Online Klaus

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Re: Tappets
« Reply #7 on: 23.09. 2015 12:05 »
Ok, in all fairness, I was just looking up the pushrod part #'s and  just down are #'s 67-0332/67-0333 (A7/10/S.T. -Tappets), but-but...what I already said; it gets a bit confusing at times

Now look what you've started; a tappet war!  ;)




It won`t take long as the Oil war  *grins*

But I know, a noisy tappet, is a happy tappet.


cheers Klaus


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Online metalflake11

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Re: Tappets
« Reply #8 on: 23.09. 2015 14:54 »
Tappet gaps do not even exist. Have a look, there is nothing there but air.
Show me a B.S.A. part number if you want to prove me wrong.
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Online Greybeard

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Re: Tappets
« Reply #9 on: 23.09. 2015 15:16 »
I bought a set of tappet gaps from Draganfly; the inlet ones were a bit large so I filed them down a little. I paid £2.50 for a set. I bet SRM charge a lot more for theirs. Mind you they are probably made of better quality air.

Online bsa-bill

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Re: Tappets
« Reply #10 on: 23.09. 2015 17:00 »
Quote
Show me a B.S.A. part number if you want to prove me wrong.

AH but there's the rub, you may find lots of Tappet this or Tappet that or Tappet adjuster, cover and so forth but you wont find a Tappet.
and (I'll say again) - and - when you adjust the Tappets you do adjust to amount of air between different Tappet bits.

Right is that clear because I think we should now move on to define Dark Matter, there's a professor Hawkins that needs our help
All the best - Bill
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1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online morris

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Re: Tappets
« Reply #11 on: 23.09. 2015 21:01 »
Just a shot in the dark, but can it be that the word "tappet" is derived from the word "tapping"?
In that case we're not talking about air, but noise... which basically is nothing but moving air... *conf2* *dunno2*
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Offline kiwipom

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Re: Tappets
« Reply #12 on: 23.09. 2015 21:30 »
hi guys, the tappets are the bits that go up and down and tap, and are adjustable, end of,cheers
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Offline duTch

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Re: Tappets
« Reply #13 on: 23.09. 2015 21:54 »

 Well, at risk of defeating my own argument;
Quote
...............
Show me a B.S.A. part number if you want to prove me wrong.
,
but I agree with ;
Quote
Tappet gaps do not even exist. Have a look, there is nothing there but air.
.......................



 I maintain this was as typo that someone took seriously and it caught on.....

Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Online Greybeard

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Re: Tappets
« Reply #14 on: 23.09. 2015 23:33 »
I believe that those highlighted parts are referring to the cam followers and their locking arrangements, not the rockers