1. Lunette
  2. Middle rail
  3. Front cross-bar
  4. Foot-board
  5. Pickaxe attachment, front
  6. Ammunition-chest keys and chains
  7. Brake-chain
  8. Side rail
  9. Spare pole
  10. Ammunition-chest
  11. Brake-lever
  12. Front ammunition-chest handles
  13. Pickaxe attachment, rear
  14. Axe and spade board-irons
  15. Middle rail
  16. Brake eye-strap
  17. Rear ammunition-chest handles
  18. Ammunition-chest keys and chains
  19. Spare-pole stirrup
  20. Spare-wheel axle-bolster
  21. Spare-wheel axle-washer
  22. Spare wheel
  23. Spare-wheel axle
  24. Toggle

The limber of the caisson has already been described. The caisson, [Fig. 64a], consists of one wrought-steel tubular axle and two Archibald wheels (57¾ in.), same as for limbers, the caisson-body, and connecting parts, viz.:

The Middle rail (central part of body formed of two angle-irons) receives the lunette in front and spare wheel in rear, and is attached to the axle by an understrap, and to the side-rails by front and rear cross-bars, with connections stiffened by brackets, and the strength at axle increased by middle-rail braces.

The Side-rails, which are attached to the axle by understraps and joined to the middle rail by the front and rear cross-bars.

The Foot-board is fastened to the middle and side rails with brackets to incline the surface of the board.

Floor-rods, passing through middle and side rails, between rear chest and rear cross-bar.

Two Road-brakes complete, and attachments for implements and spare parts.

The lever road-brake now supplied is similar to the ordinary wagon-brake, and so arranged that each side may be operated separately. The shoe is applied in rear of the wheel, and the brake-lever stands upright inside the wheels, opposite the front side of the rear ammunition-chest.

The caisson body carries two ammunition-chests same as for limber.