Hi all,
My Evo 3 Mk2A (probably) 12.5-30 mower has a long arm for the cutter clutch that sticks up from the cutter deck. You pull it back and up to engage the cutter drive and then push it down, forwards and up to disengage it. Disengaging the cutter drive also engages a cutter brake. The cutter brake is a small plate with a piece of brake pad riveted on, which gets pressed by spring onto the side of the cutter drive pulley. If the brake doesn't work there is enough remnant friction in the cutter belt to keep the blades turning even though the belt isn't under tension.
I found that out because one day I'd been incautious with disconnecting the cutter drive and hadn't pushed the cutter clutch arm all the way forward. In this middle position the cutter brake is pushed onto cutter pully with a bit of force but there is enough belt tension to keep the cutter pulley rotating at speed. The friction pad on the cutter brake got worn down to the backing metal, and no longer effectively braked the cutter on disconnection
This got tedious because in order to ensure the blades stopped after cutting I had to stop the engine as well as disengaging the cutters. See the attached pics of the cutter brake and worn pad.
This went on for some time because access to the cutter brake is difficult, so I put off fixing it until I had to get into the transmission again (separate post). I ended up lifting the back of the mower with a car jack which enabled the deck to sink to its greatest clearance from the mower chassis. That provided enough access to get spanners onto the bolts without removing the cutter deck. It wasn't clear from the manual diagrams, but the cutter brake is held in place by the nut on the end of the actuation shaft (easy to undo with long socket extension) and the nut under the cutter deck for the swivel post (OK access above blade disk). The swivel post itself may have been threaded into the cutter deck - I had to wind it up and out but it wasn't a close fit.
With the cutter brake out it was a simple matter to drill out the rivets that held the old worn pad in place - standard 5/16 in. What was difficult was getting a replacement brake pad - I ended up sacrificing a spare brake pad from a hobby car, cutting off half of the friction lining of a front pad using a hacksaw along the glue line. A relatively easy cut and left me with a slightly thinner but still OK piece of brake lining. Couple of holes and it went straight on with new rivets. The standard aluminium rivets that I had on hand didn't have as big a head as the ones that came off, but they appear to be doing the job. One gotcha is to not put the new lining onto the wrong side of the cutter brake - did that
Reinstallation was simple. I was a bit concerned that the pad being thinner might cause it to break under load, but its held up so far. If it does break then I'll happily glue a replacement in place because the heat from it stopping the cutter disk won't be sufficient to mess with a standard contact cement.
