[Fig. 3] is an enlarged perspective detail showing how the strips forming part of the expansion member or coil are connected up;

[Fig. 4] is a sectional view, on lines 5—5 of [Fig. 1];

[Fig. 5] is an enlarged detail elevation, with parts removed;

[Fig. 6] is an enlarged detail cross section of the central portion of the apparatus, with part broken away;

[Fig. 7] is a rear elevation of the same with parts broken away;

[Fig. 8] is an enlarged detail of the upper portion of the apparatus shown in [Fig. 4], with parts removed;

[Fig. 9] is a perspective detail, partly broken away;

[Fig. 10] is an enlarged detail of a portion of the ratchet mechanism shown in the lower portion of [Figs. 6] and [7];

[Fig. 11] is an enlarged section of a flexible coupling shown in [Fig. 7];

[Fig. 12] is an elevation of a modification of the expansion coil;