Bullet Proof Bulldog
Posted: Tue May 26, 2009 9:12 pm
The Walker Bulldog is a very capable tank at least in model form, but I think my aspirations were a bit to much for the basic metal kit. So I bought a pair of heavy duty gearboxes from Dave at Forgebear, and made new drive shafts to replace the short ones fitted as standard. All was well for a short time then smoke started to pour out of the tank and one RX18 unit up the creek, and with the bank holiday on top of us and my grandson coming in a few days, panic set in I had to get it going again. A quick email to Forgebear and as I was passing Dave’s home on the Saturday he arranged for me to pick a unit up from him, to which I am very grateful, so the day was saved but I decided to make the Bulldog a bit more bullet proof.
First I fitted a 5v 40mm cooling fan to the RX18 unit, and vented the case so that the major air flow went past the drive fets, it picks up it’s power from the smoke unit socket, also fuses were put in the battery and motor lines, these are 5amp on the battery and 4amp on each motor at least for now. Next was support bearings on the outside of the drive shafts to remove load from the gearbox bearings, so far so good but one thing that bothered me was the front idler wheels, they tended to look outwards when running and put a curve in the track, which I’m sure must add load to the motors. So I machined a pair of front idler wheels similar to some I had seen on a Bulldog, these would have been mounted on to a common shaft but there are two pillars in the way so I made a bracket to go around them and fitted stub shafts each side, this made the front end very solid.
The new gearboxes take up the space where the smoke unit sat so hopefully I am going to modify it to fit, apart from that the tank runs a treat plenty of power, also quieter and better slow speed control with the smother drive train.
First I fitted a 5v 40mm cooling fan to the RX18 unit, and vented the case so that the major air flow went past the drive fets, it picks up it’s power from the smoke unit socket, also fuses were put in the battery and motor lines, these are 5amp on the battery and 4amp on each motor at least for now. Next was support bearings on the outside of the drive shafts to remove load from the gearbox bearings, so far so good but one thing that bothered me was the front idler wheels, they tended to look outwards when running and put a curve in the track, which I’m sure must add load to the motors. So I machined a pair of front idler wheels similar to some I had seen on a Bulldog, these would have been mounted on to a common shaft but there are two pillars in the way so I made a bracket to go around them and fitted stub shafts each side, this made the front end very solid.
The new gearboxes take up the space where the smoke unit sat so hopefully I am going to modify it to fit, apart from that the tank runs a treat plenty of power, also quieter and better slow speed control with the smother drive train.
