I have a L123 Husquravana brush cutter and I am looking for the lock nut that holds on the trimmer head. I am looking for the size to the lock bolt.

How to Remove the Cap to Replace the Line of Homelite Trimmer


Homelite UT33600 Operator Manual General Maintenance Advancing Line...

the nut holding the trimmer head on is a left hand thread so you have to turn it clockwise to undo it
when the head is off you put the next attachment on and do up the nut in the reverse direction

There are a large number of different designs that can be fitted to almost any machine so the fitting and removal details will differ slightly but fortunately a close inspection usually reveals the process to be fairly intuitive.

A few in my experience can be removed by locking the shaft with a pin and unscrewing by hand, with a strap wrench or with a standard wrench if there is a facility. Most seem to need the trimmer head cover removing in order to gain access to the retaining nut or bolt.

This may be one of those situations where specifically applied brute force may be appropriate.

Here is a link that could be of assistance.
http://www.ereplacementparts.com/husqvarna-223r-200601-brushcutter-parts-c-114486_203804_203831.html

There is a hole just above the grass trimming head that you can slip a screw driver into. Turn the head so that the inner and outer holes align where you can put a screw driver or other hard steel object in. Put it in there and then turn the head counter clock wise until it comes off, it may take a little effort to get it to move, but you should be able to do this with your hands. Once you get the trimmer head off, put the blade on and hopefully you still have the nut and washer accessories to hold the blade in place. You will need to place your screw driver back in the alignment hole to hold the head from spinning while you tighten the blade nut back down. Make sure it is tight, you don't want that blade coming off at ~10,000 rpm!

The part number you require is 503 85 63-01

http://www.husqvarna.com/ddoc/HUSI/HUSI2004_USen/HUSI2004_USen_I0401009_.pdf

Section B shows the part you are looking for

To remove the strimmer and procut fitment first you need to lock the shaft by placing item 35 into the slot in the flange next to the fitment and through into the hole in the outer housing of the drive shaft, item 3. Then using the box spanner turn the fitment CLOCKWISE. Once this has started to move it can be turned by hand until it released. Place the brush cutter onto the shaft followed by the dished washer, cupped face towards the cutter and fix in place with the nut, turning it anticlockwise to tighted. DO NOT overtighted as the direction the cutter turns will tighten the nut further.

Look at the top of the head (where the brush cutter is) find the small hole about 3/16 diameter. Insert an allen wrench or a large nail, or anything else that will fit in the hole almost the same size as the hole. While putting a little downward pressure on this "tool" turn you blade slowly by hand until you feel the tool slide into the locking slot, this will hold the blade from turning. Keeping it in this position, take a socket and ratchet on the nut that is holding the blade and loosen and remove it. THE NUT HAS LEFT HAND THREADS SO TURN IT OPPOSITE OF WHAT YOU NORMALLY WOULD TO REMOVE IT!!!!

When the engine was running there was no drive to the cutter head. It appeared that the bearing at the bottom of the flexible drive shaft had worn away from the three crimped marks in the exterior drive tube and slipped down, thus the flexible drive shaft inside the main tube was not reaching the cutter head. I made up an exterior tube that just fitted over the main drive tube. I Drilled a 6mm hole through the exterior tube and the main drive tube into the worn bronze bearing. I then brazed a 6 mm nut onto the exterior tube and screwed a 6 mm bolt and lock nut right into the bearing inside the main drive tube. This stopped the bearing moving down and away from the interior flexible drive. The trimmer then worked as it should do. Good Luck, Tony Hillyard, Pleinesa Oeuvres, France