3020 tachometer

[JaredWardall]

Hi,
I have a 1969 John Deere 3020. However my grandpa has a John Deere 2520. The tachometer on my 3020 bounces around alot, like it won't give an exact reading. On my grandpas 2520 it is pretty exact and doesn't bounce around alot. Can you tell me how it works or if I can make it exact? Maybey modify/update it or something?

 

[Tx Jim]

Bouncing needle is probably caused from a dry tach cable. Try pulling cable out and lubricate it with Lubriplate and re-install.

 

[JaredWardall]

Ok, thanks. I'll try that. Some guy told me the needle moved by magnetic fields form the engine? It sounds weird to me but does it sound lagit?

 

[JD5210]

I sugguest you look at JD parts (URL included) to see how your tach works/looks. As TX Jim said yours works off of a cable.

On my tractor their is an engine speed sensor which contains a permanent magnet and a set of windings. The sensor is mounted close to the gear teeth of fuel injection pump. As gear turns, its moving teeth induce a small amount of alternating current in the sensor. Voltage leaving sensor travels through circuit to tachometer and to ground.

John Deere - Parts Catalog

 

[Tx Jim]

I sugguest you look at JD parts (URL included) to see how your tach works/looks. As TX Jim said yours works off of a cable.

On my tractor their is an engine speed sensor which contains a permanent magnet and a set of windings. The sensor is mounted close to the gear teeth of fuel injection pump. As gear turns, its moving teeth induce a small amount of alternating current in the sensor. Voltage leaving sensor travels through circuit to tachometer and to ground.

John Deere - Parts Catalog

'64-'72 JD 3020 tach is cable driven.

 

[jd3020u]

If you take a tach from these apart you'll find the needle mounted to a wheel. The tach cable connects to a U shaped arm that spins around the circumference of the wheel. The magnets on the arm spinning around the wheel is what moves the needle. JD parts doesn't show the inside of the tach. Call Evergreen Restoration for a new tach with the correct looking face and colors

715-635-8629
jmtrcka@centurytel.net

Do try lubing the cable but it might be the needle getting sticky. They're pretty delicate to work on once you tear into one. Other places can repair them too.