Greetings All Have a 1988 Vohl Blower, County Tractor Carrier with blower mounted on front, rear engine is a JD/Detroit 6466AF-00, looking for location of the Tach sensor, doesn't seem to be where indicated in the manual. Is there any other location the sensor could be mounted? Attached a couple pics from the manual. any help much appreciated.. Bob G
Which engine do you have? The 6466 is JD. The detroit would be an optional different engine, as far as I know. The County is what? a converted Ford is all I've ever seen so I'm confused on how either a JD or Detroit got into a County. Second pic shows a JD engine and sensor. If you don't have that, then how about a picture of the engine that is there? I'd expect a Ford to run a tachometer off the alternator "W" terminal, if it's electronic. If it's not like the second pic, or an alternator tachometer, then the flywheel area would be the next place I'd look.
Thanks for the reply, sorry for the poor description. The unit has two engines, the rear engine is/was a collaboration of DD/JD as were many of the DD’s/JD’s from what I have read. Am attempting to follow the wire back from the cab but so far no luck as I lose it in the harness but still working on that. Thought maybe it was on the flywheel end as well but not seeing it there either. The tach worked when the machine was new so there has to be a sensor mounted somewhere on the engine.
A tach drive adapter was sometimes mounted on the 6466 engine block as well. See screenshot.
The second pic is a tach generator. Ot should be easy to spot if the engine has that set up. Tachs can be mechanically or electrically operated
That looks like a fun rig to drive at 2am in a snowstorm....NOT.
When Detroit was coming close to the end of their 2 stroke era they began re-badging many different engines as a Detroit. Deere, Perkins and IH/Navistar were just some of the ones they used.
Digger Actually not a bad machine to operate, a little noisy and cold but it can move snow, had an easy life as it was an ex airport machine. Always kept inside till it retired 12 years ago. I ran this machine when i first started at the airport and then we moved on to a much bigger unit. Couldn’t stand the thought of it being scrapped so put in a bid when it it went to auction and was successful. I have 3/4 km of driveway and lots of yard so not entirely overkill, mechanically sound , needs some tlc..i knew the machine plus i got it cheap lol.
I did find there was some collaboration between JD and DD that went into the series 60 design, but that would have been later than the design of the 466jd. In any case, those wiring diagrams are different, one shows two wires from the sensor to the tach, the other shows one wire. An alternator would also only need one wire to the tach. And I'm assuming the front engine drives the tractor, while the bigger rear engine drives the blower. Just haven't been around one.
Those Vohl blowers are some of the best ever made for heavy snowfall. The city here used to use them but now uses wheel loaders with blowers on the front with seperate engines. I think one of their limitations is they don't turn very sharp.
Hi Delmer Thanks for the update on the DD/JD, i gave up on the manuals as i could not find any type or form of a sensor. Started digging around and found a wire with a push on connector, it just happens to reach the alternator, checked with a lead back to tach and it’s definitely the correct wire. Must have used a signal from the alternator but could find no reference to that in any wiring diagram in 3 manuals. Found no terminal for a tach signal on the current alternator so i assume it was changed. Not sure if i can add a wire or just order the correct alternator. Attached a pic, thankyou for your help. Bob
No pic. was posted.
Hi Dave It is definitely a bit of a tank, good for windrows or a road, used a blower as lead on runway for heavy wet snow a few times but most of the time we plowed into windrows and launched it. Runs like a top and is tough as nails, no electronics or pilot controls. Vohl definitely built great equipment but wouldn’t want to use it on city streets either.
Here is the pic
You can add the terminal if you want to open up the alternator, or you can order one with the R terminal. The tach just hooks to one of the three phase windings in the alternator, so any wire on the AC side of the rectifier, they're all the same frequency! and if the alternator is producing power, then you know it's got AC inside. https://www.dbelectrical.com/produc...63-amp-with-tach-r-terminal-stud-on-rear.html
Years ago, in a galaxy far, far away, I used to work on these. Just confirming the collaboration.
I test drove a County....when I went to "Dismount" I got my fat hips stuck between the front and back tire, my feet flailing uselessly 12" off the ground. My friend is rolling on the ground laughing, and I'm trying my best to lift my body up with my arms to then toss myself outwards. Adding a cab would only make it worse. Also, they are called the "County" because they take up most of the county to turn, their unique drivetrain severely limits the turning radius.
Wasn't aware of the Deere 440, I've sorta been looking for a 435. The 860 scrapers had a 6-71. And the infamous 8010/8020 articulated 4-wheel drive as well.
Thanks Delmer, appreciate the help.
I worked for a small city public works and we had a Vohl mounted on a 644 Deere. It was a self contained unit pinned on instead of the bucket. A bit of a PITA to install- thats why we left it on all winter. It had the Deere 466 and was about 1987 vintage. Great machine and they still have it afaik. It outlasted 2 new replacements
Digger Can sure see that happening, not much room between the tires. Glad they made the cab for the blower with a rear door
Delmer Added a wire as you suggested but still no tach, what should i have for a signal from the alternator? Attached the wire to the post without the nut, tach needle jumped a couple times but only moved a fraction of an inch. Adding throttle made no difference. Output from alternator looks normal.
That's all it is as far as I know. Maybe give the tach a few hours to see if it comes back to life? I don't know anything about the insides of an electric tachometer. That wire should have AC of something like 12-28V, can't remember. As long as the alternator is putting out 14V it should be fine on that end. You could confirm the AC voltage is the same at the alternator, and at the back of the tach, and the tach is grounded.
Will do, thank you
If thats the old Delco alternator, you need the one with the 3rd spade terminal alonside the other 2. It is a half-voltage terminal which is usually used for a tach. A lot of guys have changed out the original alternators for one with only 2 spade terminals because they are easier to find when in a pinch and then wonder why the tach doesn’t work or they don’t care as long as it charges. I can provide a picture of one if you need it