The good old 4200XL, no need of further presentation at this forum..
Recently done some upgrades of a 4200XL, that might be of interest for other operators. My friend like to operate his machine in some pretty rough, crushed road gravel, can not stick to the 'ideal' fine soil and 'beach sand', which has been a quite big 'pain' for the tracks..It's the aluminium tracks, from about 2014-2015 and on, that is now standard on all Chinese machines. Weaker design/material than the steel tracks the 4200XL was equipped with the first years (now not in production anymore). But it can be arranged to make them hold up just fine even in rough environments, with some tricks, as I will explain beneath.
The original 4200xl 'children's toy car' track motors, are naturally gone into history. Then he tried the brushless upgrade motors, which also did go 'down the tubes' long ago. Too weak, in addition to the too high rpm for this excavator's 'environment'. Then we installed my brushed upgrade kit, Soyland, which has power enough, and a more suitable speed. Problem was that stones just kept on jamming the tracks, and the 2 Amp fuses on the motors kept breaking often. When putting on larger fuses, the track links were often just ripped off instead. Ideally there should better be some kind of a 'slip clucth' on the motors, which is complicated and needs too much space. What we did is 'shaving off' about 2-2.1 mm of the height of the track gears, sprocket wheels', in the lathe. Now the track gears just 'jumps' on the pins when tracks gets jammed by stones. The operator see what's going on, get the chance to stop and reverse the track, possible lift the track off the ground to clear it for stones. Have installed 5A fuses now, instead of the 2A, which did run 'hot' when the track gears start slipping. The point at which the gears starts to 'jump', or slip, can to some extend be regulated by the tension of the track tension spring (which is originally missing on the 2011-2014/2015 versions,, and makes a smooth operating of the tracks even more difficult in the first place). Running in course gravel, generally we try to keep the tension of the springs as 'small as possible', to the point the tracks just want to jump off, to allow stones getting jammed, to be easier 'spitted out'.
In addition some cover plates are installed up close to the track gears, to help keeping stones away.
The idea of small teeth on the track gears are now used by one of the new Chinese competitioners too the Eagle/Rc4wd company. That's the picture of the grey coloured undercarriage. Those teeth are almost not visible, but actually works. I didn't want to take off that much of the 4200xl teeth, no need to, better to remove less than more as a start. The motors on the current 4200xl is more powerful than on this other machine, so can deal with larger teeth. Same tracks as the Eagle/4200XL. It' seams to be the new thing. Eagle/Rc4wd have not yet discover it, looking at the new Volvo. But maybe they soon 'see the light')
As mentioned above, if just operating in fine soil and sand, things are not so critical.
