Rehashing old tach idea

[lmichael]

Hmm, interesting idea. I did order this. 85mm 0-4000RPM With Hour Meter Tachometer Gauge Diesel Engine 9-32V For Car Boat | eBay
Cheap enough. I'll need to make a wire harness and get a mount for it. I'm thinking of some type of triple pod type, that can house this, my oil pressure and a temp gauge. Maine issue is I'd have to mount something like that on top of the hood. Not so bad as I can make a harness to do that but, my oil pressure gauge is a mechanical type. I can route wires easily enough for opening and closing the hood, but that plastic oil tube would be an issue. Unless I sell the mechanical gauge and get an electronic one. Then I'd only need to make one harness. Got all the stuff to make a nice harness that will look "factory".
Would anyone be interested in a really nice AutoMeter mechanical oil pressure gauge?

 

[GreensvilleJay]

curious as to how you wired your 'w' wire and if you have an internal schematic of the alternator?
here's what one guy did ,from another site.... 'P' is for Pulses.....

 

[lmichael]

Pretty sure exactly what you see on this schematic. Found a vid of a guy doing this on a Denso from a Dodge Cummins. Same layout and design just scaled up from the miniature in the Kubota.
The field coils have exposed connections around the outer ring. So all I had to do was remove the sheet metal cover and tied into the end of the field coil. Exactly what they did on the Cummins.

 

[edritchey]

Curious why you need a tach…

In 20+ years never “needed” one on my BX2200.

Do use the tach on the B2910 if using the rotary cutter (Brush hog) though…

I do understand want VS need…

I added one to my old 2005 BX23 so I could find out what speed I needed to get 540 from the rear PTO shaft while my manual says to run wide open it always seemed to be to fast and just like I thought it was a few hundred more RPM than I needed to get the rear PTO to 540 All of the BX models after the 30 series came with tachs as far as I know not sure why they didn't put them on the early models.

 

[lmichael]

The tach I ordered should be here this week. I need to make some way to install it (housing or such) but I will do a temp hookup just to see if it works. BTW pretty sure it's a 3 phase alternator as there are 6 field connections around it.

 

[GreensvilleJay]

Probably 99.44% of alternators are 3 phase units. Even the super amp ones , actually TWO 3 phase units in one case.

 

[lmichael]

Well, I guess I did something wrong. My meter says I am seeing 7.25VDC not AC voltage. I guess those terminals are on the wrong side of the rectifier

 

[lmichael]

OK, thankfully I wired in at 2 different points. I have one that does in fact trigger the tach. But sadly the instructions while they show wiring to the alternator and adjustment it does not give information on how to set it for a 3 phase alternator. just indicates "speed ratio = gear number" What? Plus I can't calibrate it with my optical tach, because I've hopelessly misplaced that, (though I did find the box)
So I ordered yet another. Story of my messy life

 

[PaulL]

I spray with my B2601. So agree totally. Pick the gear, set the revs to a known good point, HST to the floor, I know I'm getting the application rate I expect. Works fine on the flat, not so good on hills (the HST slips a bit).

 

[lmichael]

I spray with my B2601. So agree totally. Pick the gear, set the revs to a known good point, HST to the floor, I know I'm getting the application rate I expect. Works fine on the flat, not so good on hills (the HST slips a bit).

Been trying to do that, and I am getting fairly good at it. My Honda was simple. I had the tach, set to 2200 rpm, put the hydro lever to full "mow" speed. It had an interesting control. There was a detent on the lever so I could hit the same every time.
Been trying to go off engine "pitch" but I've not been as successful as I was with the Honda. In any case I am on the way. My buddy and I are going to build a wire harness for it so it all looks OEM.

 

[lmichael]

BTW, the seller sent me a fuel gauge as well as a "gift". Has anyone added a fuel gauge to one of these G series machines that only have a low fuel light?

 

[GreensvilleJay]

If your alternator 'guts' is wired the same as a BX23S is, the center of the 'Y', is connected to ground through a diode ,so you will see a positive pulsing signal. You can't measure it with a DMM as they sample about 3Hz( 3 x a second ). You need an oscilloscope to 'see' the pulses.
Calibration requires what the alternator pulley size and the crankshaft pulley are . Several websites will have the 'math' posted.Say crank is 4", alt is 2". If engine RPM is 2000, alt is spinning at 4000. But then you have to divide by 3 as only 1 pulse per rev, so 4000/3=1330 ?
As for fuel gauge, you'll need the sending 'mate' to that gauge. senders are simple low value variable resistors with a known 'empty' value and a known 'full' value. Those values are usually posted in a chart in the WSM electrical section.

 

[lmichael]

If your alternator 'guts' is wired the same as a BX23S is, the center of the 'Y', is connected to ground through a diode ,so you will see a positive pulsing signal. You can't measure it with a DMM as they sample about 3Hz( 3 x a second ). You need an oscilloscope to 'see' the pulses.
Calibration requires what the alternator pulley size and the crankshaft pulley are . Several websites will have the 'math' posted.Say crank is 4", alt is 2". If engine RPM is 2000, alt is spinning at 4000. But then you have to divide by 3 as only 1 pulse per rev, so 4000/3=1330 ?
As for fuel gauge, you'll need the sending 'mate' to that gauge. senders are simple low value variable resistors with a known 'empty' value and a known 'full' value. Those values are usually posted in a chart in the WSM electrical section.

Yeah, on the calibration it has a calibrate function. So when my new laser tach gets here, I will set that up, and adjust as called for.
As for fuel gauge. As an old professional mechanic I know full well "how" they operate (believe me I've dropped enough gas tanks in my day) IDK which job I hated more, dropping a gas tank or doing exhaust work.
Anyway the reason for my question is my G2160 has a low fuel light. So, my assumption is the sending unit is a simple on/off type sensor (switch) with a float.
I was simply wondering if anyone has done this on a G2160 and what they found as a sending unit that is workable.

 

[lmichael]

OK, so today weather cleared up a bit and I snuck the machine into my main garage. Received the laser tach yesterday (but pouring rain and we were fridge shopping).
Got, a strip of tape on crank pulley, took readings with laser tach, then simply calibrated the analogue to the laser at idle, 2000 rpm and 2500 rpm to confirm calibration and everything is working like it should. This week or next my buddy and I will build a wire harness and get it all mounted up.
I will put up some photos once I have it done. Otherwise I am quite pleased. Also glad I chose to use a 2 wire connector to hook up to the alternator. As I figured even if one of the connections was a "miss" (which it was, I could check the second one. I will simply just not use the second wire in that connector.
BTW I ordered a "pocket Oscilloscope" today. It should be here Wed and I will play with it and post photos (if I can) of the wave form I see off the output. Gotta love Amazon $26 for what looks like a really nice little pocket scope.

 

[lmichael]

Well, my new little O Scope came and today I finally had time to hook it up to the alternator lead I found that drives the tach. And as promised, here is a link to it and a photo of what I saw when looking at the my homemade "W" tap. I'd call the whole adventure successful! Leaving the link to the scope because you never know if something like this could be useful. And at under $30 it's a low risk investment 【Upgraded Model with 10X Prode] FNIRSI Digital Oscilloscope DSO152, Handheld Portable Automotive Oscilloscope with 2.8 inch TFT, 2.5MS/s High Sampling Rate, 200KHz Bandwidth: Amazon.com: Industrial & Scientific
Sorry about the glare from my shop lights. But it gets the point across. This was at idle (about 1050 RPM) as measured by my laser tach.

 

[GreensvilleJay]

nice...it works...
sigh, $30 for a scope, even if it is 'audio' range and heckuva DEAL.might have to buy 2 just to have......