To reduce servicing hours by applying the constitution that an arm type suspension device is formed out of front and rear arms rotatably connected to a frame, front and rear axles provided so as to cause slide contact between adjacent ends of both arms, and front and rear slippers detachably fitted to the contact position of both arms.

Regarding an arm type suspension device for a triple axle, arms 2 and 3 are installed on a frame 8 so as to be rotatable about horizontal shafts 9 and 10. Front axles 4 are independently provided on the front part of the front arms 2 and the rear axles 5 are provided, two at front and rear positions, and at the front and rear positions of an oscillating body 12 laid so as to be rotatable about the intermediate horizontal shaft 11 of the rear arms 3. In addition, wheels 13 and 14 are journalled to both sides of each of axles 4 and 5. In this case, slippers 6 and 7 are detachably provided at the contact position of both arms 2 and 3, and each of the slippers 6 and 7 is formed out of a short piece 15, a long piece 16 and a suitable number of bolt holes. The slippers 6 and 7 are detachably provided at the rear lower side and the front upper side of the arms 2 and 3, using bolts 18.