US2498375A

US2498375A - Ladder lock

Info

Publication number: US2498375A
Application number: US697875A
Authority: US
Inventors: Francis W Moore
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-09-19
Filing date: 1946-09-19
Publication date: 1950-02-21
Anticipated expiration: 1967-02-21

Description

Feb. 21, 1950 w, MOQRE 2,498,375

LADDER LOCK Filed Sept. 1.9, 1946 2 Shets-Sheet 1 FIE-1* IN VEN TOR. FRANCIS MIA/[00. 22

F. W. MOORE LADDER LOCK FenZL1950 2 Sheets-=Sheet 2 Filed Sept. 19, 1946 INVENYTOR. FHA NLI'IEWMU [IRE Patented Feb. 21, 1950 UNITED S TAT ES PATENT OFF 1 CE LADDER LOCK Francis W. Moore, Tiflin, Ohio Application September 19, 1946, Serial No. 697,875

10 Claims.

This application relates to a ladder, the inclination of which is adjustable, and where a lock is provided to hold the ladder in adjusted position. The particular improvement relates to the lock provided for this purpose. The object of the invention is to provide a ladder which may be locked in adjusted inclination .and securely held at that inclination until intentionally adjusted, and a lock that can be readily released for adjustment. More particularly, the invention relates to a lock where there is pivotal adjustment between parts, and locking cams are provided which prevent such pivotal movement until the cams are intentionally released. Further details of the invention will appear as the description proceeds.

In the accompanying drawings forming a part of this specification, Fig. 1 is a side elevation of the lower part of a ladder which hassteps thereon automatically maintained in parallel with the .foot of the ladder and means to lockthe ladder at adjusted inclination. Fig. 2 is .a detailed view of the lock and one ladder step with the ladder locked at an inclination. Fig. ,3 is a side View of the lock shown in Fig. 2 taken along the line 3-3 of Fig. 2. Fig. 4 is a side elevation of a rung ladder with a foot at the bottom and a shoe at the top which are maintained parallel, and means for locking the ladder in adjusted inclination to the foot and shoe. Fig. 5 is a side View of a rung ladder having a foot and means for locking the ladder in adjusted inclination to the foot. Fig. 6 a side elevation of another ,form of lock suitable for use as the lock in Fig. 5', with a portion of the foot removed. Fig. 7 is a reduced side I elevation of the lower end of the ladder, shoe and lock shown in Fig. 6 with the cams removed for clarity of illustration.

In the form of ladder shown in Figs. 1, 2 and 3, there is a series of steps 1:0,, the upper surfaces of which are normally maintained horizontal. For this purpose, there is a side strip H and a side strip [2 to which. the steps are pivoted at l3 and M respectively. It will be seen that adjustment of the relative position of the strips. will simultaneously adjust the inclination oi all of the steps Ill, since the equal distance apart. of. the pivots on the strips and on the several steps and foot enforce a parallel link motion. Suitably mounted on strip H- there are pivotv pins [5, l6 and I! 3:

v2 vided with an arm 24 pivoted to strip [.2 at 125. It will be noted that the axes of the cams are parallel and spaced to permit contact before the rises vof the cam directly face each other.

Normally, the ladder is supplied with afoot 2.6 which has a lower surface parallel with'the upper surfaces of steps Ill and which :is pivoted 'to strips I land 42 by pins-21 and .28 respectively.

It will be seen that, when foot 216 rests on a horizontal surface, steps 10 will have upper hori zon-tal surfaces :at' whatever-angle to the vertical strips II and I2 may be adjusted.

Presuming that the ladder has been adjusted to either the vertical position in which it is shown in Fig. 1 or to the slanting position in which it is shown in Fig. 2. it will be readily seen that attempted movement of the top of the ladder to the left will be resisted by contact of cams '19 and 20, while attempted movement of the upper .end of the ladder to the right will be resisted by contact of cams l8 and I9. When adjustment of the ladder is to be made,,the respective cam 18 0126 which resists the desired movement of the ladder is released by means of projecting pin 21 or 22 which extend outward to form releasing handles. Thus, by simple release of the appropriate cam, the ladder can be readily adjusted and, when in adjusted position, the spring .23 retainsthe locking cams in contact with camlBso as to prevent movement of the ladder in either direction.

In the construction shown in Fig. 4, there is a similar foot 26 with its pivots f2! and 2B, but instead of strips 1 l and 12 there is a main ladder side strip 30 provided with rungs 3| and 32 .and an adjusting strip .33 connected to pivot 28. A shoe .34 at the upper end of the ladder is pivoted'to strip 30 at and to strip 33 at 36. The shoe 34 is thus maintained in proper relation with foot 26 so that, when foot 26 rests upon a horizontal surface, the left side of shoe 34, as shown in Fig. 4, will be vertical and may rest against any upright surface against which the ladder is leaned.

In this case, thestrip 30 is provided with a plate 31 carrying pivots .38- and39 on which there are pivoted cams 4-0 and 41 provided with pins, and .43 connected by asprin-g 44. Cam 4] is provided with an arm 45 pivoted at 46 to strip 33-. In the form shown, it will be seen that the contact of cams 4D and 4| will resist'movement of th upper-end of the ladder to the left but the cams maybe readily released for adjustment by movementof cam 48 by the extendedv handle 'justm'ent in both directions.

It will be seen that this look operates substantially the same as the lock shown in Figs. 1 to 3 except that it is locked against movement in one direction only. An additional locking cam, as shown in Fig. 1, might be used with this form of ladder, and the ladder shown in Fig. 1 could be supplied with a one-way lock only, if desired.

Fig. shows a look similar to that shown in Fig. 4 where the ladder consists of sidepieces 50 and rungs 5| with afoot 52 to which the side strip is pivoted at 53. In this case, cam 54 surrounding pin 53 is attached to turn with strip 50 about the pivot. A cam 55 is pivoted to the foot at 56. Pin 51 on cam 54 is connected to pin 58 on cam 55 by means of a spring 59. It will be seen that the spring normally holds cam 55 in contact with cam 54 and that-the contact of these cams will lock the ladder against movement of the upper end of the ladder to the left, as viewed in Fig. 5. When it is desired to adjust the'upper end to the left, extended pin 58 may be employed as a handle to release cam 55 so that the required adjustment may be made.

Figs. 6 and 7 illustrate a construction in which there is a ladder side strip 60 mounted on a pin 6| in a foot 66, similar to the arrangement in Fig. 5, but in which the ladder is locked against movement in either direction and throughout a wide range of movement, so that the ladder can be adjusted to any position about pin 6i and locked in that adjusted position against movement in either direction.

In this case, there are

cams

52 and 63 keyed to'pin 6| along with side strip 60 so that all turn together. The throws of cams 62 and 63 are in opposite directions. Arranged symmetrically about pin 6| there are

pins

64, 65 and 66 mounted in the foot 60. Onpin 65 there is a cam 61 having thereon a pin 68. On cam 62 there is a pin 69 connected to pin 68 by spring 10 which urges cam 61 into contact with cam 62. On pin 66 there is a, cam 1|, having a pin 12 connected to a pin 73 on cam 62 by a spring M. On pin 64 there is a cam 15 having a pin 16 connected to a pin 1'! on cam 62 by a spring I8. It will thus be seen that these cams 61, H and 15 are all normally urged into contact with cam 62. In the construction shown, cam H will resist move- .ment of the upper end of the ladder to the right,

while cam 15 will resist movement of the ladder to the left.

Similarly, there are cams I9, 89 and 81 held in contact with cam 63 by means of springs,

springs 82 and 83 being shown, but the spring in connection with cam 19 being behind the cams and so not visible. It will be noted that cam 80 will resist the movement of the top of the ladder to the left while cam 8| will resist the movement of the top of the ladder to the right.

As will be seen, by the construction disclosed in Figs. 6 and '7, the central cam may turn through any angle and still be locked at any ad- The cams may be released by separate movement of their pins but, of course, in practice some suitable-means not shown could be employed for simultaneously releasing the cams that lock the ladder against movement in the direction in which adjustment was desired.

It will be noted that, in each instance, the lock is accomplished by preventing the rotary movement of a locked cam in contact with one or more locking cams, with the locking cams spring-held against the locked cam, and the lock being releasable by movement of each spring-x held cam in opposition to the spring. In the preferred form shown in Figs. 1 to '3, there are three cams, the central one of which is locked by the other two. In the construction shown in Figs. 4 and 5, there are but two cams, and the lock is operative in only one direction. In the construction shown in Figs. 6 and 7, there are two central cams and they are locked continuously in both directions by a series of locking cams there around, in this instance three locking cams for each locked cam. With the three cams arranged as indicated in Fig. 6, the central cams are constantly locked at any angle to which they may be adjusted.

While primarily designed for use in combination with a ladder, particularly in such a combination as shown in Figs. 1 to 3, the lock may be capable of application in other combinations where similar demands are to be met. While several modifications have been shown and described, it will be understood that other changes may be made within the scope of the appended claims while retaining some of the advantages of the invention.

What I claim is:

1. In a ladder having side strips and a member pivotally mounted on said strips, a locked rotary cam connected to the strips and member to be turned by pivotal adjustment of the strips and member with respect to each other, and a locking cam oscillatable about an axis which is at a fixed distance from and parallel with the axis of the locked cam, resilient means normally pressing the locking cam against the locked cam with the rises of the cams so related that turning of the locked cam in one direction tends to bring their rises together, and means to turn the rise of the locking cam away from the locked cam.

2. In a ladder having side strips and a member pivotally mounted on said strips, a locked rotary cam connected to the strips and member to be turned by pivotal adjustment of the strips and member with respect to each other, and a locking cam oscillatable about an axis which is at a fixed distance from and parallel with the axis of the locked cam, pins projecting from the cams on the same sides of their axes as their rises, and a spring connecting the pins, the pin on the locking'cam'being extended to form a handle for releasing the lock.

3. In a ladder having side strips and a member pivotally mounted on said strips, a locked eccentric cam connected to the strips and member to be turned by pivotal adjustment of the strips and member with respect to each other, and an eccentric locking cam oscillatable about an axis which is at a fixed distance from and parallel with the axis of the locked cam, pins projecting from the cams in the same sides of their axes as their rises, and a spring connecting the pins, the pin on the locking cam being extended to form a handle for releasing the lock.

4. In a ladder having a foot pivoted thereto, a lock for locking the ladder in adjusted pivotal relation to the foot comprising an eccentric locked cam and at least one eccentric locking cam, said cams being mounted so that the locked cam is turned with respect to the axis of the locking cam when the pivotal relation of the foot and ladder is changed, resilient means pressing the locking cam against the locked cam in a direction to move their rises together, and means to move the rise of the locking cam away from the locked cam for adjusting the angle of the foot 'tothe 1adder." I

5. In a ladder having a foot pivoted thereto, a lock for locking the ladder in adjusted pivotal relation to the foot comprising an eccentric locked cam and at least two eccentric locking cams, said cams being mounted so that the locked cam is turned with respect to the axis of the looking cams when the pivotal relation of the foot and'ladder is changed, resilient means pressing the locking cams against the locked cam in a direction to move their rises together, and means to move the rises of the locking cams away from the locked cam for adjusting the angle of the foot to the ladder.

6. In a ladder having a foot pivoted thereto, a lock, for locking the ladder in adjusted pivotal relation to the foot, comprising locked eccentric cams mounted to be turned by adjustment of the ladder with respect to the foot and with their rises extending in opposite directions, three eccentric locking cams equally spaced around each locked cam, and resilient means urging the looking cams against the locked cams with their rises so arranged that the turning of the locked cams is resisted in both directions at any position to which the locked cams are adjusted.

7. In a ladder comprising two parallel side strips at each side of the ladder and steps pivoted to said strips by pivots equally spaced on the two strips and on the several steps, providing a parallel link adjustment, a lock for locking the ladder in adjusted position, said lock comprising three eccentric cams mounted on one of the strips on parallel axes, an arm extending from the middle cam and pivoted to the other strip, resilient means urging the outer cams against the middle cam" with their rises in such relation that turning the "middle cam on its pivot in one direction is resisted by one of the side cams and turning it in the other direction is resisted by the other cam, and means for moving the rise of either side cam away from the rise of the middle cam.

8. In a ladder comprising two parallel side strips at each side of the ladder and steps pivoted to said strips by pivots equally spaced on the'two strips and on the several steps, providing a parallel link adjustment, a lock for locking the ladder in adjusted position, said lock comprising three eccentric cams mounted on one of the strips on parallel axes, an arm extending from the middle cam and pivoted to the other strip, the rises of all three eccentrics being on the same side of their axes, resilient means urging the rises of the outer cams toward the middle cam, and means'to move the rise of either outer cam away from the middle cam for adjusting the ladder.

9. In a ladder having two side strips at each side of the ladder, steps and a foot pivoted to the stripsby pivots equally spaced on the two strips on each side; and on the several steps and foot,

the foothaving a flat bottom and each step hav ing a flat' top maintained parallel with the said fiat bottom by the parallel link motion about said pivots, a lock for locking the strips, steps and foot in adjusted relation, said lock comprising three eccentric vcams mounted in a row on parallel axes on one or said strips with their rises extending from the? same side of their axes, resilient means to urge the rises of the outer cams towards the rise of the middle cam, the perimeter of the outer cams being normally in contact with the middle cam, and an arm extending from the middle cam and pivoted'to the other strip on the same side of the ladder.

10. A lock'f or pivotally related parts comprising an eccentric locked cam mounted on one of said parts, an eccentric locking cam mounted upon an axis parallel with the axis'of the locked cam, the axes'-of the cams being at a fixed distance apart permitting the peripheries of the cams to meet before the rises are directly towards each other, resilient means urging the rise of the locking cam towards the rise of the locked cam, and means forcing the locked cam to turn when the pivotal relation of said parts is changed.

FRANCIS W. MOORE.

REFERENCES CITED UNITED STATES PATENTS Name Date Shain May 26, 1891 Number