Tweet
Refurbishment of a pawl unit - these get very little notice or attention
On rebuild of DDG I had to deal with a Pawl/Cancel unit that seemd to be intermittently "shorted" and the actual pawl was sticky.
The sticky part was as suspected, dried up lubricant, so the body was duly taken apart, cleaned out and lightly smeared with grease and then a drop of oil. Do not fire loads of grease in there.
The floating contact was cleaned up and floats on 3 springs, watch and not drop / lose one like I did as I was very lucky to have a busted spare to borrow from.
The "short" ended up being where it seemed to have been arcing on switch, so I had to carve out that trough, is suspect worn copper plus grease left it part conductive, explains why the original hold on coil looked like it had been in a microwave
The wires were also cleaned off the ends and tinned again, soldered to the contacts with new material and then filed flat not to foul the contacts.
Thats it, nothing complex, dont use rough material to clean the copper, ususally if you clean off the material and use a pencil eraser it is sufficient to clean up the copper very well.
On rebuild of DDG I had to deal with a Pawl/Cancel unit that seemd to be intermittently "shorted" and the actual pawl was sticky.
The sticky part was as suspected, dried up lubricant, so the body was duly taken apart, cleaned out and lightly smeared with grease and then a drop of oil. Do not fire loads of grease in there.
The floating contact was cleaned up and floats on 3 springs, watch and not drop / lose one like I did as I was very lucky to have a busted spare to borrow from.
The "short" ended up being where it seemed to have been arcing on switch, so I had to carve out that trough, is suspect worn copper plus grease left it part conductive, explains why the original hold on coil looked like it had been in a microwave
The wires were also cleaned off the ends and tinned again, soldered to the contacts with new material and then filed flat not to foul the contacts.
Thats it, nothing complex, dont use rough material to clean the copper, ususally if you clean off the material and use a pencil eraser it is sufficient to clean up the copper very well.
The Gold Standard of course would be the magnetic-cancel... needs one magnet and two sensors. FWIW My timeout was designed for about 12 seconds; this served me very well for many years but in modern traffic condiitions I think it now needs to be longer - say 20 seconds or even more!
Comment