B-60 (K-161T) Interlock Module

[rmaynard 14,952]

Pictured below is the electrical system of a B-60. This machine has the K-161T engine with a magneto ignition. Item #21 is described as an interlock module. Does anyone know what exactly this little can is/does.

I have not been able to start the engine yet, but I am a little suspicious of this item since the wire coming from it which is supposed to go to the condenser is disconnected, and a new condenser has been wired in.

 

 

 

 

 

[buckrancher 2,678]

I would think its like a neutral safely switch so you can not start in gear

[gwest_ca-(File Mod) 10,548]

Wiring diagram

 

Connected to the condenser would be the same as connecting to the points or magneto kill wire.

 

Garry

[slammer302 2,154]

I have a b-60 and I had the same question I ended up removing it and she runs great

[rmaynard 14,952]

According to the wiring diagram, it looks like you have to depress the clutch while starting. Now I can see that with electric start, but I generally need two feet on the ground when I yank a starter.

Guess I'll have to read the owners manual and see what it says.

Edited November 24, 2014 by rmaynard

[Geno 1,928]

I have a b-60 and I had the same question I ended up removing it and she runs great

 

Was it a switch Slammer or just a round piece with wires coming out of it?  

[slammer302 2,154]

Just a round piece with wires this what it looks like without it

[rmaynard 14,952]

It must be "important" because Toro still sells it for about $75.00.

[slammer302 2,154]

I will have to look and see if I still have mine laying around

[Geno 1,928]

It must be "important" because Toro still sells it for about $75.00.

 

They make it sound important that's for sure!      I'd almost lay dollars to donuts there's a tiny little 15 cent resistor molded in that big expensive piece of plastic...  Does the coil on that have an internal resistor or was it supposed to be external? 

 

That would also explain Slammer's running better after it was taken off...

Edited November 24, 2014 by Geno

[rmaynard 14,952]

It's a magneto under the flywheel with external point and condenser.

[rmaynard 14,952]

I found the patent number for the module. Here is a description of what this little thing does.

 

Ignition magneto safety interlock
US 3726265 A

ABSTRACT

Circuits for controlling the starting of an internal combustion engine that has a magneto ignition system including a primary winding that can be shorted to prevent ignition. The circuits include a position-responsive switch and an electronically controlled switch to selectively control a shorting switch that is, in use, connected across the primary winding of a magneto. In the preferred arrangement, the shorting switch is normally nonconductive and is maintained nonconductive (1) when the position-responsive switch is closed, indicative of a condition in which it is acceptable to start the engine, or (2) when the electronically controlled switch is changed from its normal level of conductivity in response to the running of the engine. When the position-responsive switch is opened before the motor is started, the normal condition of the electronically controlled switch permits the shorting switch to be made conductive by the spark producing pulse and thereby prevents ignition. The position-responsive switch is actuated through a transmission of the engine being controlled and in the embodiment shown is normally closed when the transmission is in neutral.

Got that?   

Added picture:

 

 

Edited November 25, 2014 by rmaynard

[slammer302 2,154]

I could of used this thread over the summer

[gwest_ca-(File Mod) 10,548]

These go with the patent description which is quite large.

 

Garry

 

[km3h 543]

If I read this right, this will ground out the ignition when the key is turned off causing the engine to shut down. 

[gwest_ca-(File Mod) 10,548]

The ignition switch on it's own will shut the engine off the way the tractor wiring diagram shows it. With the key ON to start the engine the module must ground the ignition also unless the clutch switch and the pto switch are both closed.

Once there is coil output the module must open the ground so it continues to run with the clutch switch and pto switch open.

 

These switches are the same switches used on the C-Series in 1977.  The poor online parts lists for 1976 show different switches but can't find a wiring diagram for them. The A-Series rear engine riders also used this modeule with the B&S engines.

 

Garry

[buckrancher 2,678]

to start the tractor you must have the pto off turn the key switch on put your foot on the clutch pedal and push it down then pull the recoil starter

 

Brian

[rmaynard 14,952]

I'm pretty sure that I have the wiring diagram for the 1976 B-60. As soon as I find it I will post it.

 

Brian - Sometimes it's difficult to pull that recoil from the drivers seat. I can see why this was defeated.

 

Edit - here is my B-60 wiring diagram. Apparently it is the same as the one in your file above Garry.

Edited November 26, 2014 by rmaynard

[buckrancher 2,678]

I start mine standing next to it using my left foot on the clutch pedal and pulling the recoil

 

Brian

[slammer302 2,154]

I just set my parking brake then get off and pull start it but as I stated above I removed the interlock device

[rmaynard 14,952]

Today it is raining and cold, and the heater is working well in the garage. The wife's car is out since she is at work today, so I have a 12 x 24' clear space in which to work. So I pushed the B-60 into the garage and started to work on the wiring and the fuel system.

 

I cleaned the fuel pump and made sure it was working. It had been bypassed with the fuel line going straight to the carburetor from the tank.

I cleaned the carburetor. Not bad.

I put a new shut-off valve and grommet in the bottom of the fuel tank. Grommet was cracked and leaking.

I replaced the fuel filter.

 

The ignition switch was okay.

The PTO interlock was okay.

The clutch safety switch was not working, so I replaced it.

I cleaned and reset the points to .020" and replaced the condenser.

My coil had some suspicious looking cuts and cracks in the control wire, so I replaced it with one taken from a K181.

 

Next, I installed the old interlock module. It didn't seem to make any difference whether it was wired into the safety circuit or not, I still had spark. So my opinion is that it is bad. I have a new one coming from eBay.

 

Anyway, after a little coaxing, I got the engine to run, and run it did. Purred like a tiger. No smoke, no knocks, no unusual noises. Transmission worked great in all gears.

 

 

[bmsgaffer 2,043]

Video!?

[rmaynard 14,952]

Video!?

Sorry, no video.