Title:
Sliding ladder jack
United States Patent 2438791


Abstract:
This invention pertains to sliding ladder jacks. In painting high walls the practice has been to set up two extension ladders to lean against the wall, attach jacks to the rungs of each ladder at a desired height, and place a trestle on the jacks to extend between the ladders. After painting...



Inventors:
Russell, Albert A.
Application Number:
US73521447A
Publication Date:
03/30/1948
Filing Date:
03/17/1947
Assignee:
Russell, Albert A.
Primary Class:
Other Classes:
182/117
International Classes:
E06C7/16
View Patent Images:



Other References:
None
Description:

This invention pertains to sliding ladder jacks.

In painting high walls the practice has been to set up two extension ladders to lean against the wall, attach jacks to the rungs of each ladder at a desired height, and place a trestle on the jacks to extend between the ladders. After painting the area which can be easily reached from the trestle in one position, the trestle is removed and the jacks are each removed and hooked in a different position on each ladder, and the trestle replaced. All of this consumes a great deal of time that otherwise might be used in painting. The structure of extension ladders is well known to the trade, as also is the structure and use of ladder jacks. Some attempts have been made to construct and use sliding ladder jacks but these have not met with success when applied to the common extension ladder, therefore specially constructed ladders were used.

However, these ladders were limited to their particular use, and were usually cumbersome and awkward.

In view of this, one of the objects of my invention is to provide a sliding ladder jack which is adapted to operate on common extension ladders now widely used by the trade.

Another object is to provide a sliding ladder jack which can be easily applied to a ladder after it is set up in working position.

Another object is to provide such a jack which has the moving parts enclosed so they will not be likely to entangle with ropes or cables used in elevating the jack.

Another object is to provide a sliding ladder jack which will operate on common two section extension ladders and secure engagement at any position along said ladders, when extended to any desired degree, by a plurality of latches engaging in.the rungs of either or both sections.

Another object provides the inclusion of means for securing the engaging latches in inoperative position.

A still further object is to provide specific means for rolling and guiding the jack body over the ladder rails, and for accommodating this means to the changes of dimension and position of ladder rails as the jack slides from the lower section to the upper section.

Other objects will appear hereinafter.

I attain the foregoing objects by means of the devices and construction shown in the accompanying drawings, in which Figure 1 is a side elevation of one form of my sliding ladder jacks; Figure 2 a top plan view thereof; Figure 3 a vertical section therethrough taken substantially on line 3-3, Figure 2, and showing the rung latches in engaging position; Figure 4 a similar section showing the rung latches in disengaged position, and the position of the ladder rail rollers when the jack is on the lower ladder section; Figure 5 a similar view showing the position of the rollers when the jack is riding on the upper ladder section; Figure 6 is a front elevation of the jack; and Figure 7 a front elevational view of a pair of ladders with jacks attached illustrating the use of the jacks.

Similar numerals refer to similar parts in the several views.

The ladders on which jacks of the type here concerned are used are of substantially standard construction and include a lower section 2, an upper section 3 and a joining means 4 for the overlap between the sections. The lower section is always wider than the upper section and the side rails of the upper section nest between the rails of the lower section at the overlap. The body of each jack consists of a two part case 5 hinged on one side at 7 and provided with hinge butts 8 with removable pins 9 on the opposite side.

The top or front case section 12 is laterally shaped to conform to the rails of both sections of the ladder as they are related at the overlap and has four rollers 14 positioned to ride on the side rails 15 of the lower ladder section 2, and four rollers 16 adapted to ride on the top face of the rails of the upper ladder section. On the inner face of this case part latches 17 are pivotally attached to lugs 18. These are arranged to swing from the outwardly extended position shown in solid lines, Figures 3 and 5, to the depending non-engaging position shown in Figure 4.

A link 21 connects cross piece 22 on each of these latches so that they work in unison in moving from engaging to non-engaging position.

Link 21 extends outward through a slot in outer case section 12 and carries a disengaging dog 25.

This is pivotally mounted on an outer portion of the link and has a pad 26, which when turned to engage the face of 12 holds the link out from * the face and this, in turn, draws the latches downward and holds them in this position so that they will not engage the ladder rungs.

Each latch I7 includes two parallel fingers 28 joined near the middle by a cross piece 22 which gives it an H-shaped appearance, in plan. The link 21 connects at each end to lugs on these dross pieces. The bottom edges of the lugs are positioned to engage the top surfaces of the ladder rungs while the inner top portions engage the bottom faces of lugs 18, which also form stops 29 to limit their upward swing beyond the extended position shown. Angle stops 29a attached to the inner face of case part 34 act as additional stops. Springs 31 operative on the lug hinge pins 32 operate to normally hold the lugs in outwardly extended or engaging position.

When drawn downward to lie parallel to the inner face of part 12 they are under tension of these springs, and when dog 25 is turned- so that pad 26 holds the link outward, it is effectively retained in position by this spring tension.

The bottom or back case part 34 is equipped with four rollers 36 on each side near the top and bottom adapted to engage the under side of the side rails of the lower ladder part. At the sides and near the top edge of case part 34 there are wide rollers 38 mounted to swing from an extended position, as shown in Figure 4, while engaging the lower ladder section, to an inwardly directed position, as shown in Figure 5, where they engage the bottom faces of the side rails of the upper ladder part 3. Springs 39 on the hinge pins 40, mounting these rollers, normally urge them to the inwardly directed position. When engaging the upper ladder part the roller supports 42 move beyond the dead center position, at right angles to the lower face of the rails of upper ladder section 4, and indicated by dotted lines A-A, Figure 5, until stopped by contact with a lug 44 on the side of case part 34. This construction gives a substantial rolling contact, on the under side of the ladder sections, as the case is run up or down the upper section 3 of the ladder I.

Each case part has an adjustable trestle bracket on its outer face. These are similar to ladder jack brackets now in general use. Bracket 46 is attached to case part 12, and bracket 47 to case part 34. Since the ladders I, Figures 1 and 7, lean toward the wall 50, bracket 46 is used to support the trestle 51 when painting is done on the upper part of the wall. As lower portions of the wall are reached it is necessary to use the brackets 47 on the inner case part, so as to place the trestle as near to the wall as possible.

In use, extension ladders I are first set up against wall 50, as shown in Figure 1, then cases are clamped on the lower ladder sections 2.

Clamping is accomplished by opening the sections 12 and 34, placing them over the ladder part, and inserting pins 9. The hinging action is shown by dotted outline 53, Figure 2. Trestle brackets 46 or 47, as desired, are then extended and the trestle 51 placed on the corresponding brackets of each case 5. Ropes 56 passing up over blocks 57 and attached to lugs 58 on the cases, may then be used to raise the jack cases and trestles to any height desired along the ladders. As each jack case moves up its ladder the latches contact the ladder rungs and are depressed from extended position as the rungs are passed. Whenever a case is lowered the latches, urged by their springs 39, assume the extended position and engage on the top of the ladder rungs. Since the upward motion of each latch is limited by its stop 29, this forms an effective way of stopping and latching the case at any position on the ladder. Both latches on each case move together by reason of the link and thus double strength is provided.

When it is desired to lower the jack cases they; are raised sufficiently to move the latches to the down position, and then dog 25 is turned to the position shown in Figure 4 to hold the link out and the latches in this down or released position. From the foregoing it will be seen that I have provided sliding jacks for holding each end of a painting trestle which can be securely held at any position along the length of any standard extension ladder by latches operative within an enclosing case; means are also shown for rendering the latches inoperative, and for easily attaching and detaching the jack case from the ladder. Much of the labor required in setting up and changing the height of painting trestles is thus avoided, the structure is stronger than the usual single jack brackets, and the structure is adaptable to fabrication to provide ample strength.

In view of the foregoing, I make the following claims with the intention that they should be liberally interpreted.

I claim: 1. A sliding ladder jack for use on extension ladders having upper and lower sections, comprising a case having a front and a rear part hinged together by laterally positioned hinges, rolling means on said case sections for engagement with the side rails of both upper and lower ladder sections, vertically spaced rung engaging latches hinged to the inner face of said front case part adapted to move from an extended edgaging position to a depending non-engaging position, stops on said case to limit the upward swing of said latches to said extended engaging position, a link connecting said latches so that they swing together, springs normally holding said latches in extended position, a dog operative on said link adapted to engage the front face of said front case part to hold said link outward so that said latches are maintained in non-engaging position, and trestle brackets attached to the outer faces of both front and rear case parts.

2. A sliding ladder jack for use on extension ladders of the type wherein the rails of the lower 5 part are more widely separated than those of the upper part, comprising a case having a front part and a rear part hinged laterally to open and close over said extension ladder sections, said case parts being shaped to substantially enclose the sectional contour of said ladder parts and provided with rollers adapted to bear on both sides of the side rails of each ladder section, trestle brackets attached to the front and rear faces of said case, hoisting means adapted to raise and lower said case upon said ladder parts, and rung engaging mechanism including rung latches hinged to the inner face of said case in vertically spaced relation and positioned to engage adjacent rungs on said ladder sections, adapted to swing from a determined inwardly extending engaging position to a downwardly depending non-engaging position, spring means normally urging said latches to said engaging position, a link connecting said latches so that they swing together, and a dog operable on said link to releasably hold said latches in non-engaging position.

3. In a sliding ladder jack, for use on section ladders, as herein disclosed, having a case adapted to engage the side rails of section ladders, rollers mounted on brackets hinged to the under side of said case having hinge pins with springs normally urging said-brackets to an inwardly extended position adapted to bear on the under surface of either ladder section, said inward movement of said bracket being limited by a stop on said case positioned to carry said rollers beyond dead center relative to the under face of said ladder sections.

4. A sliding ladder jack for use on extension ladders of the type wherein the side rails of the lower section are spaced to include the side rails of the upper section, including in combination, a case removably attached to said ladder and adapted to embrace the rails of both sections thereof in sliding relation, means for hoisting said case on said ladder, trestle brackets on said case, and means on said case for engaging the rungs of said ladder including latches inwardly hinged on said case adapted to swing from inwardly extended rung engaging position to a depending non-engaging position, stops on said case to limit the swing of said latches to said extended position, spring means urging said latches to extended position, and means for releasably holding said latches in non-engaging position.

5. A sliding ladder jack for use on extension ladders of the type having the side rails of one section separated to a greater width than those of the other section, including a case adapted to enclose said ladder and having rollers for slidable engagement with the side rails thereof throughout the entire length thereof, trestle brackets on said case, a lug on said case for attachment of hoisting means, and means for engaging the rungs of said ladder to prevent downward movement of said case while permitting upward movement thereof, including spring tensional outwardly extending latches hinged to and operative on the interior of said case and adapted to normally engage over the rungs of said ladder and to swing downwardly to non-engaging position when said case is moved upwardly on said ladder, together with means for releasably holding said latches in downward non-rung-engaging position.

ALBERT A. RUSSELL.