I am a civvy DMI at SEME. I would like to know the in- depth answer to this question. A Tracked vehicle (let's take the 432) is travelling at 20mph. The Bottom of the track is travelling at 0mph. What speed is the rest of the track travelling at? I thought it was 40mph at the top for it to 'catch up'. Upon discussing it with another Instructor I now realise that surely the track will still be doing 20mph as would the Final drive and the rest of the running gear. Please enlighten us with your world of Technical knowledge, expertise and guesswork. Thanks. Grizz.