RPM

how can I be sure my recently restored Lister D is running at the reccommended 1500 RPM? CJ

Colin, Surely thats pushing it for a D, if its a 1.5 Hp its 750 rpm and 2 Hp is

1000 rpm.

Mart> how can I be sure my recently restored Lister D is running at the

An incandescent light bulb flashes one hundred times a second, I think the same is true of a fluorescent but some have high frequency electronics.

So a white spot on the flywheel appears stationary at 750, 1500, 3000 and 6000 rpm.

Three equidistant spots on the flywheel should appear stationary at

1000 unless my arithmetic is wrong.

AJH

If you haven't got or can't borrow a handheld tacho, count the number of firings in a period of say ten seconds timed on your watch. Multiply by six to get the number of firings in a minute, and as it's a four stroke, multiply the answer by two to give you rpm.

A tacho is easier though, and allows you to observe speed variation. They come up on eBay from time to time.

Regards, Arthur G

There was a 2 1/2hp version also I think... ttfn Roland

I've just read DE's history of the D and it only mentions 1.5 and 2 unless its an F that Colin has got.

Mart> There was a 2 1/2hp version also I think...

firings in a period of say ten seconds timed

as it's a four stroke, multiply the answer

Arthur your acuity of hearing is only to be admired! :-) I should be so lucky, eh?

Tom

firings in a period of say ten seconds timed

minute, and as it's a four stroke, multiply the answer

Hi Martin, how far down your ear do you stick the Tacho?

-- Dave Croft Warrington England

Depends which ear Dave, the fifty year old or the 21 year old, obviously the fifty year old has seen more of life, so will take a little more ;-)

snip

Incandecesents don't really flash, the tungsten doesn't cool down enough between phase changes to make them useful, you're right about standard fluorescents though. A neon mains indicator or any mains freq gas lamp can be pushed into the same service, small neons only in the dark :-).

50 * 2 * 60 = 6000 and whole multiples or divisibles of 6k sounds good to me, but I suck at maths ! :-)

Cheers, Scruttocks

What's that you're saying, Tom? :-)

You make a good point. As a rough indicator, it does work after a fashion for slower engines, though admittedly 1500rpm would be hopeless, as the sound just tends to be a brrrum.

I was (probably wrongly) assuming that it really only did 750rpm like most Lister D engines I've known.

Regards, Arthur G

"Tom" wrote

Wassat you say? Speak up young man, I can't hear you :-).

You make a good point. At 1500rpm the ear method would be useless as the engine just makes a brrrm noise. I was assuming (probably wrongly) that it did actually run at 750rpm, like any of the Lister Ds I've known.

Regards, Arthur G

Sorry about repeat posting, OE is being objectionable this morning.

-- Arthur G

======== Well, actually . . yes, the current does flow through the filament one hundred times every second, but . . . the filament remains glowing so you won't get the stroboscopic effect in an incandescent lamp, nor with the quartz halogen type, which also has a filament.

Even with most fluoros, the tube is internally coated with a high-persistant fluorescent material to minimise the observed flicker.

However, you will get the stroboscobic effect with gaseous discharge types such as neon, xenon, etc. which re-ignite every half cycle, or a LED which fires every cycle.

JW² =======

A couple of people have queried this. Let me assure you that using a clear bulb, 240V, standard light does produce a usable strobe effect.

Just to be sure I have switched on my old Dual record turntable which has a built in neon and strobe markings around the perimeter of the platter. Using a 40W bulb and shrouding the built in neon I can see the markings appear to be stationary, albeit not as clearly defined as when viewed under the neon.

AJH

I picked up a hand held rev - sorry - tachometer at a Wessex club crank u p a couple of weeks ago. It is actually a voltmeter (I think) that reads in RPM. The meter has a two core lead that plugs into the generator. This has two fittings, a linier speed wheel and a blunt pointed rubber ended probe that you stick in the dimple at the end of most mainshafts, a product of their manufacture.

It's good fun, made me go around starting up engines & see how close my guess was!

I used to count the Crossley 1075's exhaust strokes & times them by two to get an RPM figure.

Regards,

J. Kim Siddorn,

Speaking of good fun, just come home from watching "The World's Fastest Indian"....

Tom