NH 1920 Fusible Link rating?

   / NH 1920 Fusible Link rating? #1  

grcutter

Member
Joined
Jan 3, 2016
Messages
38
Location
Patterson, NY
Tractor
2000 NH 2120, 1999 NH 1920, 1986 Ford 1710
I have a 1999 NH 1920 which I bought used a few years ago.
When the starter motor went out last year (bad solenoid contacts), I discovered that the previous owner had replaced the fusible link with something that looks like a 30A fuse.
I didn't think much about this since it was starting just fine.
But several times, recently, I have had problems starting where I hear the solenoid click but the starter motor does not come on.
When this happened, I checked on this 'fuse' and found it really hot to the touch. But each time that I got around to debugging this, the tractor started just fine.
So I took a closer look at this 'fuse' and from the part number it is really a 30A Pollak relay.
This model Pollack has a resistor inside that will heat up and keep the relay open if you keep trying to start.
(Type II: Non-Cyclic Blade Terminal Circuit Breakers)
If I wait until this relay cools down, then I can start the tractor just fine. And these are not hard starts. This engine fires up on the first click.

Does anyone know why a Pollack relay would have been used in place of the fusible link?

Does anyone know what the solenoid current draw would be in normal operation?

I'm thinking of removing this relay and going back to the fusible link.
Does anyone know the current rating of the original 1920 fusible link?

The manual says that the fusible link it there to protect the rest of the tractor from over-current events. If this event is not related to starting, then something else in the tractor is drawing too much current during operation. Any ideas of what I should be looking at?

Thanks in advance!
 
   / NH 1920 Fusible Link rating?
  • Thread Starter
#2  
Can someone explain the purpose of the fusible link?
From looking at the schematic, everything on the non-starter side of this link is already protected by regular fuses with the start switch in the ON position.
During normal operation (ON), it would appear that the only current flowing through the fusible link would come from the alternator to charge the battery.
Is the fusible link there to protect just to protect the alternator in the event of a battery short?
Is this Pollak relay tripping trying to tell me that there is a potential battery problem? I would not guess this since it cranks just fine when it starts.
 
   / NH 1920 Fusible Link rating?
  • Thread Starter
#3  
Answering my own questions here just for reference:

The original fusible link is Yazaki FLWX-0.85. There appears to be a new part number which is HR085-21A.
The wire appears to be 18 AWG which has an ampacity of 16A. The fusible link appears to be rated for 21A.
Various auto parts stores sell fusible links with 18 gauge wire. Belden 784690 is one example.
1720807218955.png
 
 
Top