Procedure for Installing Hyd & Mech Thumb
1) The Stick Boom has to be flat and clean of all objects to weld the mounting plate on
2) Curl Stick Boom into position you would for transporting the excavator and clamp or tack weld the thumb to the Stick Boom, make sure it is flat on the boom, and as close to the bucket pin as possible
3) Have to check for clearance next. Curl bucket as far as it will go into thumb and check for a minimum of 1/2 “ clearance. If you do not have this you will have to move the thumb up the boom to get this clearance. Than check for the clearance between thumb tips and main boom with stick fully curled into main boom, this should be minimum 1 “. If you do not have this you will have to move the thumb down the stick boom. The mounting plate of the thumb can be trimmed as need on the main mount end to get this clearance.
4) Once you have checked this clearance and it is okay you will have to extend thumb to check how it meshes with the bucket. If this is okay put thumb back into it stored position and it is ready to be welded
5) The mounting plate and boom should be pre heated to appox 200 deg F. They can be welded with E7018 or T91 Flux Core. Three stringers of 1 / 16 “ wire or 5 / 32 rod. Where the mounting plate has to be welded on, on the main mount end around the end and 18 “ up each side, at the plug hole and on each side of plug 16 “ long, and on tube end on the cut slope and down 12 “ on each side. Do not weld across the small end of the mounting plate on the tube end.
6) Max pressure on hydraulic thumbs should not be more than 2000 psi