Folding crank for extensible ladders
US 399313 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
P. S. BRADFORD.
FOLDING CRANK FOR EXTBNSIBLE LADDERS.
No. 399,313. Patented Mar. 12, 1889.
, k ml PELEG t BRADFORD, OF BRIDGEVATER, NASSAUIUSETTS.
FQLDENG CRANK FOR EXTENSIBLE LADDERS.
SPECIFICATION forming part of Letters Patent No. 399,313, dated March 12, 1889.
Application filed December 13, 1888. Serial No. 293,513. (No model.)
To (LZZ trim/1t may concern:
Be it known. that I. .IELue S. BRADFORD, of Bridgcwater, in the county of Plymouth and State of Massachusetts, have invented new and useful lnu rovements in Folding Cranks for Extensible Ladders. of which the following is a specification.
in the accompanying drawings, in which simi lar letters of reference indicate like parts, Figure 1 is a side tdevation of any extensible ladder closed and provided with my improved crank. Fig. 2 is a central vertical section of the same partially raised or extended. Fig. 3 a sectional detail of the crank.
A represents the lower ladder-section, B the central. section, and. C the upper. The lower section, A, is provided near its upper end with clamps (I, (not ncwin l'lllSlllVO1ltl01l, secured to said section, and bent around the edg s oi? the rails of the section. 13, which is adapted to slide up and down. therein. Secured to the lower end of the section I) are similar clamps, Znwhieh bend around the edges of the rails of section A.
c 0 represent two pairs of clan'ips placed one pair above the other, secured to the upper portion of section i3, and bendingaround the edges of the rails of section l) l) are swinging for supporting the ladder, pivotally secured at their upper ends to the upper portion of the section A.
E is a barrel or drum fixed upon the shaft c, supported by the section A, and whose end is squared to receive a crank.
F is a rope, or the mechanical equivalent thereof, secured at its lower end to the drum or barrel Fl, passing over a pulley, ll, sus pended from the cross-piceeA, supported by the upper ends oi. the rails of the section A, and secured at its other end to one of the rungs (preferablythe lowest) in the section 13.
l a rope, or the mechanical equivalent thcreot', secured at one end to the cross-piece A, passing up over the pulley J,which is suspended. from a cross-piece, 3, secured to and supported by the upper ends of the rails of the section l5, and down to one of the rungs (preferably the lowest of the section (1, to which its other end is secured.
Now, it a crank be applied to the shaft c, the rope F will cause the section B to slide up on the section A, and at the same time the rope I will cause the section C to slide up on the section 15, so that as soon as the section B has been raised to its full height the section C will be found to have been raised to its full height above the s ction 13. Thus it will be seen that (at a tire, for instance) time enough only is required to raise one section of a ladder divided. into three sections, each of which is necessarily shorter than a section of a ladder of the same length divided into two sections. Thus time is saved and the ladder shortened, the latter being an important advantage in transportation.
An ordinary ratchet, K, is provided for holding the ladder-sections in a raised position. I
My improved folding crank consists of the main portion, ll, placed upon the squared end of the shaft c, and the handleport-ion N, pivoted at n to said main portion. 1 is a spring secured at one end at Z to the portion L, and provided at its other end with a project-ion, P, preferably rectangular in shape. That end of the handle which is pivoted to the main portion is semicirculzn in shape, and is provided with two depressions, N and N. The depression N is pnactically rectangular in shape, while the depression N has one side cut away or rounded, as shown in Fig. 3. \Yhen the handle N is in position for use-- that is to say, at right angles to the portion Lthe projection 1 lies in the opening N and securely locks said handle, as shown in Fig. 3: but by lifting the free end of the spring P the projection l is withdrawn from the depression N, and the handle N can be turned back. and laid parallel with the portion L, in which position the projection 1 lies in the depression N". Inasmuch as it is desirable that the handle should be capable of being placed in positionv for use without the slightest delay, one side of the depression N is, as above stated, cut away or rounded, so that although the pressure of the spring and projection l P sulticient to hold the handle closed, still, if force be applied to it, the said projection readily slips over the rounded portion between the depressions N N and allows the handle to be swuu up and locked in the position shown in Fig. 3.
Having thus fully described my invention, one end to said main arm L, and provided 10 what I claim, and desire to secure by Letters I near its free end Withaprojeetion, P ,adapted Patent, is to drop into said notches, substantially as and In an extensible ladder, the combination, for the purpose described.
5 with the hoisting mechanism thereof, of a PELEG s. BRADFORD. crank mechanism conslstlng, essentlaiiy, of
the main arm L, handle N, pivoted to said \Vitnesses:
main arm and provided with thenotehes or de- HENRY WV. TILLIAMS,
pressions N N, and the spring P, secured at J. M. IIARTNETT.