RIDING IN HELPERS COMPARTMENT OF 14-TON TRACK MOTOR - HAD BOTH FEET RESTING ON RAISED LIP OF COMPARTMENT. MOTOR JUMPED TRACK - JERKING AND WHIPPING EE. THIS ACTION CAUSED BOTH FEET TO SLIP OUT OF DECK OF COMPARTMENT AND BE ROLLED BETWEEN MOTOR AND RIB. BROKE 5 BONES IN TOP OF FOOT.