Stihl line trimmer head

[1Alpha1]

I have a new / unused Stihl SuperCut 20-1 line trimmer head. I've had it for years and don't have any idea as to where I got it, or why.

It is a single line model. I've disassembled it and examined it closely. According to arrows on the line spool inside the head, line can be wound in either direction. There is a ratcheting pawl that allows you to turn the spool one-way only though.

For the life of me, I can't figure out how the line advances, as there is no "bump head" on it. The cover is flat and it doesn't move up or down once you press it back onto the head.

This head should fit my FS-250R. My question(s) is this. What would be the benefit of a single-line, and how does the line advance, if there is no bump knob on the cover?

Anything you guys can tell me about this particular type of head will be appreciated. I have a Stihl AutoCut C 25-2 line head ordered. It will be an improvement on the head that came as OEM on my FS-250R.

Pic of the 20-1. Although the pic shows two lines, the head I have is only one line.

Pic of the inside:

Pic of top of line spool:

Pic of bottom of line spool:

 

[Full Chisel]

Is that the type where you thread a single strand of line through and turn it to wind the string up? Those are nice if so, I have a Shakespeare easy wind head on the Echo trimmer and it works great. Not familiar with that particular model though. The Stihl heads I have used in the past left a lot to be desired.

 

[Full Chisel]

I wonder if that has some type of clutch that automatically feeds out line?

 

[1Alpha1]

I don't know a whole lot about this type of head. I don't see it being able to feed the line w/o the head having to be disassembled. I found plenty of pics of the 20-2 head, but few if any, of the 20-1. The 20-2 looks to be a two line head.

I'll keep looking for more pics of the 20-1 and post them up as I find them. That aluminum pawl on the inside must have something to do with feeding the line. Problem is, I can't figure out how it works since there is no bump knob. As I mentioned, the cover is relatively flat and it snaps into place and doesn't move.

BTW......there is no way to wind the line from the outside. You need to remove the cover and pull the line spool out to load it.

 

[opinion]

Supercut heads are automatic feeders. The head senses when the line is short and automatically shoots out. It measures from the head to the blade on the deflector and gauges off of that. I don't know the innerworkings of it. Don't sell much of it to care.

 

[alderman]

Seems like only one line would vibrate a lot.

 

[1Alpha1]

I went ahead a loaded up some line per directions. Directions showed winding the line in a counter-clockwise direction on the spool. Yet, the spool only rotates in a clockwise direction. When you manually rotate the line spool, it draws the line in, instead of allowing it to feed out.

WTF..............

I did call a Stihl dealer and he said that he'd never seen a model 20-1 feed head. He spoke to one of his techs, and the tech said the same thing. Both had no idea as to how it functioned. I was told to bring it in and they'd figure it out. Looks like that's what I need to do.