[614] & [615]. Sections of rubber tyres.
Wheels are also made with rubber rings applied between the boss and shaft so as to allow a limited amount of elasticity between the wheel and axle.
Section 36.—EXPANDING AND CONTRACTING DEVICES.
Common expedients for these purposes are—jointed folding rods, as a carpenter’s rule; the telescope tube; net work; diagonally crossed and jointed bars; lattice work; springs (see [Section 80]); lazy tongs ([No. 623]).
[616]. Telescopic ram hydraulic lift. (See also [No. 1217].) Consisting of two or more rams sliding within each other.
[617]. Parallel bar expanding grille, or gate.
[618]. Parallel bar expanding grille, with lazy tongs motion, each alternate bar has slotted holes as shown.
[619]. Modification of [618]. The number of horizontal bars can be multiplied indefinitely.
[620]. Venetian blind; this method is used also for movable doors or partitions, sliding horizontally.