Farm Equipment - AC 7040 RMP Tachometer

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AC 7040 RMP Tachometer

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=48293
Printed Date: 27 Aug 2025 at 2:24pm
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Topic: AC 7040 RMP Tachometer

Posted By: SSLivestock
Subject: AC 7040 RMP Tachometer
Date Posted: 01 Apr 2012 at 10:34am

Just curious where does the Tachometer hook up in the engine compartment on a 7040 Mine only works about half the time.

Replies:

Posted By: Lynn Marshall
Date Posted: 01 Apr 2012 at 4:11pm

The tach senses the speed from the alternator.There's no mechanical cable or drive if thats what you are looking for,it's all electrical.Check your connections at the alternator and at the back of the engine where the engine harness connects to the cab harness.I guess a wire could even be loose at the back of the tachometer head.Does the tractor charging system seem to operate?