PTO Rev Counter

[pycoed]

Main rev counter on my Zetor 7045 is a bit temperamental & sometimes on a cold morning doesn't register for a half hour or so. This is not usually a problem , but I've recently resurrected a Japa 100 buzz saw which needs to run at a specified PTO speed (400 rpm). Mindful of flying tungsten carbide inserts from the saw , I thought I'd better try to get a better rev readout.
You can buy digital rev counters complete with a magnetic pickup sensor & neodymium magnet for around £8 online. I'd previously used one on my Kubota engined Cushman Truckster which didn't have a rev counter cable. Rev counter worked fine, but I found that 400RPM on the PTO was less than 1000 rpm on the engine, at which speed the Kubota produced about 4 hp & the saw could be stalled on a toothpick, hence the decision to use the tractor, at least until I can find/make/bodge a reduced box for the Cushman PTO.
Found a bit of ally plate about 3/8" thick & turned a hub out of some ally bar & pressed the two together drilled & filed to fit over PTO splines ( a complete waste of time actually - if I do this again, I'd just make it a slide fit over the splines), drilled & tapped for a couple of grub screws to hold in place & drilled & tapped for the magnet in the outside edge. Bent up a bit of steel strap to hold the pickup & fitted to one of the PTO guard bolts.

I had a plastic knockout box lying around , so fitted the Digital revcounter to that along with a switch & mounted on inner wing. There was a convenient permanent 12v feed just near the handbrake so I used that with a switch to energise the setup, rather than run an ignition feed back from the dash .

Wiring these is dead simple - it's just +12v, earth & the sensor feed to the readout. Sensor pickup comes with three wire leads , again +12v , earth & the sense wire (these are brown, blue & black for the line, earth & sense respectively on the the two sets I've used

 

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Main rev counter on my Zetor 7045 is a bit temperamental & sometimes on a cold morning doesn't register for a half hour or so. This is not usually a problem , but I've recently resurrected a Japa 100 buzz saw which needs to run at a specified PTO speed (400 rpm). Mindful of flying tungsten carbide inserts from the saw , I thought I'd better try to get a better rev readout.
You can buy digital rev counters complete with a magnetic pickup sensor & neodymium magnet for around £8 online. I'd previously used one on my Kubota engined Cushman Truckster which didn't have a rev counter cable. Rev counter worked fine, but I found that 400RPM on the PTO was less than 1000 rpm on the engine, at which speed the Kubota produced about 4 hp & the saw could be stalled on a toothpick, hence the decision to use the tractor, at least until I can find/make/bodge a reduced box for the Cushman PTO.
Found a bit of ally plate about 3/8" thick & turned a hub out of some ally bar & pressed the two together drilled & filed to fit over PTO splines ( a complete waste of time actually - if I do this again, I'd just make it a slide fit over the splines), drilled & tapped for a couple of grub screws to hold in place & drilled & tapped for the magnet in the outside edge. Bent up a bit of steel strap to hold the pickup & fitted to one of the PTO guard bolts.

I did similar to this using an inductive proximity switch bolted to the pto guard with no need for a magnet the proximity switch is set close to the pto release button & signals a digital tach in the cab of the tracto.

 

[Classichay]

They’re great I use them on my older lathe and horizontal mill for read outs, never thought to use them on a tractor pto as the pickups aren’t entirely water proof.

 

[pycoed]

They’re great I use them on my older lathe and horizontal mill for read outs, never thought to use them on a tractor pto as the pickups aren’t entirely water proof.

I wondered about the waterproofing - I covered the cable from inside the cab down to the sender with heat shrink, shrunk onto the back of the threads. Time will tell how effective that will be - it's certainly being tested at the moment!

 

[:-]]

They’re great I use them on my older lathe and horizontal mill for read outs, never thought to use them on a tractor pto as the pickups aren’t entirely water proof.

I wouldn't let that stop you, mine has been on the tractor around 7 years & it wouldn't break the bank if it had to be replaced. I use it to accurately run 540 rpm off the 1000 shaft to save fuel.