GB1590221A

GB1590221A - Ladders

Info

Publication number: GB1590221A
Application number: GB2796776A
Authority: GB
Original assignee: GRAVITY RANDALL Ltd
Current assignee: GRAVITY RANDALL Ltd
Priority date: 1977-10-05
Filing date: 1977-10-05
Publication date: 1981-05-28

Description

(54) IMPROVEMENTS RELATING TO LADDERS (71) We, GRAVITY-RANDALL LIMITED, a British Company of Slinfold, Horsham, Sussex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to ladders having tubular metal rungs which interconnect tubular metal stiles or side members, the end portions of the rungs being passed through aligned bearing holes in the inner and outer walls of the stiles. These ladders are hereinafter referred to as of the kind described.

Ladders of this kind are usually made of light aluminium alloy and the fixing of the rungs in the hollow stiles has always been a problem. The most common methods of rung-fixing have involved first the formation of a shoulder at the inner ends of the end portions, passing the end portions through the holes in the inner and outer walls of the stiles and spinning or swaging over their extremities against the outsides of the stiles.

The present invention consists in a method of making ladders of the kind described which comprises putting the two ladder stiles close together side by side, passing the rungs through the holes in both stiles so that they project from the stiles, upsetting the extremities of the rungs, separating the stiles so that they abut the upset extremities and expanding the end portions of the rungs within the hollow stiles and/or against the inner faces of the inner walls of the stiles.

The invention further comprises apparatus for carrying out the method and a ladder made in accordance with the method or by the apparatus.

For upsetting the rung ends a pair of clamps may be provided to grip the rung between the extremity and the adjacent stile but leaving the extremity projecting. A punch or each of a succession of axially movable punches may be provided to bear on the extremity of the rung and upset it. In one form this is done in stages by two punches which act in succession. The first punch is shaped simply to flare the rung end; the second punch completes the turning over of the extremity. Complementary die parts may be provided to cooperate with the punches.

Alternatively the extremity of the rung may be folded outwards to form a flange of double thickness.

Each extremity of each rung could be upset individually but clamps and punches are preferably provided to perform similar operations on both ends of a rung simultaneously.

When the upsetting is done in two or more stages, sets of punches and clamps are preferably provided side by side to enable the stages to be performed simultaneously on adjacent rungs, the ladder being moved along rung by rung to enable all the upsetting operations to be performed on each rung in turn.

After the rung extremities have been upset the ladder is moved on to another station for the final fixing of the rungs. This is preferably done quite separately after the extremities of all the rungs on a ladder have been upset. It would be possible, particularly with long ladders, after a few rungs have been upset for the end of the ladder to reach the final fixing station and for the final fixing operations to proceed while rungs further along the ladder are still being upset. Tubular ladder stiles are usually sufficiently flexible to allow the necessary bending of the stiles between the upsetting station where they are close together and the final-fixing station where they are wide apart.

At the final fixing station means is preferably provided to hold the stiles firmly against the upset rung extremities. The rung extremities may also be pressed endwise between axially movable coining dies to ensure that the upset extremities are correctly formed and their turned-over edges are fully in contact with the outer walls of the stiles.

The coining dies may be combined with expanding mandrels shortly to be described.

The expansion of the rung within the hollow stile or against the inner faces of the inner walls of the stiles is preferably done by an expanding mandrel inserted in the rung end and expanded to barrel the portion of the rung between the inner and outer walls of the stile or beyond the inner walls thereof.

The expanding mandrel may be of split sleeve form made of metal but is preferably an elastomeric sleeve, of rubber for example, which expands radially on being compressed axially. One proprietary rubber with a very good fatigue life which makes it very suitable for an application of this kind is sold under the trade mark AVOTHANE.

One advantage of the method of rung fixing according to the invention is the possibility of avoiding the machining operation to form shoulders on the rung against which the inner walls of the stiles can abut. These shoulders have usually been formed by machining off the end portions of the longitudinal ribs which are extruded on the rungs to provide a tread surface. In ladders made in accordance with the invention and provided with longitudinal ribs, the ribs continue through the openings in the inner wall of the stile. The expanding mandrel preferably extends into the rung beyond the hole in the inner wall of the stile to cause a bulge in the rung against the inner face of the inner wall and to ensure that the rung is expanded tightly in the hole in the inner wall. This improves the appearance of the joint by removing the clearance between the rung and hole necessary for insertion and for accommodating the tread grooves which may be quite shallow.

The rungs could be of generally circular cross-section but are preferably non-circular.

A cross-section which is generally triangular but with curved sides and rounded corners affords a wide tread surface. Square and hexagonal are other possible general forms of cross-section.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which, Figure 1 illustrates stages in the manufacture of a ladder by one method according to the present invention, Figures 2 and 3 are cross-sectional views of alternative forms of rungs, Figure 4 is a plan, and Figure 5 a front elevation of apparatus for assembling ladders according to the invention.

Figure 6 is an enlarged section on line 6-6 of Figure 4 Figure 7 is a fragmentary plan view further enlarged of parts shown in Figure 6 Figure 8 is an enlarged section on line 8-8 of Figure 7 Figure 9 is an enlarged section on line 9-9 of Figure 4 Figure 10 is an enlarged section on line 10-10 of Figure 5 Figure 11 is a further enlarged fragmentary section of part of Figure 10 at a later stage in the operation of the apparatus.

Figure 12 is a view similar to Figure 11 of a modification Figure 13 is a view similar to Figure 12 at a later stage in the operation of the modified apparatus.

Figures 14 to 16 are fragmentary crosssectional views on an enlarged scale of a modification of part of Figure 4.

Figure 17 is a cross-sectional view of a modified form of rung-fixing according to the invention.

Before the manufacturing stages shown in Figure 1 are carried out a pair of stiles in which rung holes have previously been pierced are arranged side-by-side with the corresponding rung holes aligned and a rung is pushed through the holes in each rung position.

In Figure 1 the stiles are numbered 1 and the rungs 2. At stage (1) punches bear axially on the opposite ends of the rung to flare the rung ends. At stage (2) another pair of punches acts similarly on the flared rung ends to complete the rolling over. At stage (3) the stiles are separated to bring them against the rolled-over rung extremities 3. At stage (4) expanding mandrels are inserted in the rung ends to swell the parts 4 of the rung inside the stiles. The expanding mandrels are combined with coining dies which bear on the rung extremities when the mandrels are urged one towards the other. The coining dies grip the rung endwise and shape the rung extremities 4 finally and urge their edges fully into contact with the outer walls of the stiles 1.

The method as described may be performed on rungs of various cross-sections.

Typical rung cross-sections of generally triangular form but with curved sides 5 and rounded corners 6 are illustrated in Figures 2 and 3. In Figure 2 rectangular section longitudinal ribs 7 are formed along the side of the rung which is intended to form the tread 8. On the other two sides are formed shallow sharp-edged ribs 9 of triangular crosssection. These are arranged in groups of three. In Figure 2 there are two groups of three on each side. In Figure 3 all the ribs are like the ribs 9 of Figure 2 but there are more groups and they are closer together and extend not only along the two sides flanking the tread part 8 but around the rounded edge 10 opposite the tread part 8.

The apparatus shown in Figures 4 and 5 comprises a stacking platform 11, on which pre-assembled rungs and stiles are put to be fed to the apparatus, a loading platform 12 in front of the stacking platform 11 and at one end of the assembly line, and in turn along the line, a rung-upsetting station 13, a stile separating station 34, a rung-fixing station 14 and an unloading platform 15.

The pre-assembled ladders are moved by the operator one by one from the stacking platform 11 to the loading platform 12 which has a grooved guide 16 at the forward end to space the ladder stiles slightly apart, a steady 17 at the rear end to keep the stiles in line and side guides 18 to locate the rungs in the stiles.

The operator pushes the ladder through the grooved guide 16 and a similar grooved guide 19 at the start of the rung-upsetting station 13 until the first rung is in the range of a first indexing unit 20. The first indexing unit 20 comprises two fingers 21 each mounted on a shaft 22 which is reciprocable, for example by hydraulic or pneumatic cylinders 23, and angularly movable to raise the tips of the fingers above the level of the rungs and to swing them below that level.

For each rearward stroke of the shaft 22 the fingers are lowered and for each forward stroke they are raised so that the ladder is moved forward by one rung pitch on each forward stroke.

Next to the first indexing unit 20 is a multiple press 24 having two pairs of clamps 25, one pair on each side of the two stiles, for gripping the rungs between their extremities and the stiles. Two further pairs of similar clamps 26 are provided further along the line and spaced from the clamps 25 a distance equal to the rung pitch. The clamps of each of the pairs of clamps 25 and 26 are mounted for opposite vertical movement, one towards the other to grip a rung and away from one another to release the rung. This movement is effected by hydraulic or pneumatic cylinders 27, 28, mounted respectively above and below the platform level. The clamps 25 and 26 are opened to allow the ladder to be moved forward one rung pitch by the first indexing unit 20 and then closed to grip the rungs presented to them. In line with positions in which the clamps 25, 26 hold the rungs are punches 30, 31 moved axially towards and away from the rung ends by hydraulic or pneumatic cylinders 32. The punches 30 are shaped simply to flare the rung extremities as shown at stage (1) in Figure 1. Complementary die parts are formed in the ends of each pair of clamps 25 to co-operate with the punches 30. When the punches 30 have flared the extremities of the rung, the clamps 25 are opened, the ladder moved one rung pitch forward and the clamps 25 and 26 re-closed. The clamps 25 now grip a new rung; the clamps 26 the previously flared rung. The punches 31 associated with the clamps 26 are shaped to curl over the previously flared rung ends as shown at stage (2) in Figure 1. There are complementary die parts provided on the ends of the clamps 26 to co-operate with the punches 31.

As the ladder is indexed forward the front ends of the stiles enter a grooved guide 33 and the ladder progresses towards the stileseparating station 34. When the upsetting of the rung extremities has been completed on all the rungs of the ladder, the ladder extends through the stile-separating station 34 (see Figures 6, 7 and 8) at which there is a separating mechanism comprising a pair of, horizontal, angle section members 43 parallel to the ladder axis and each having an upright arm 35 at each end. The arms 35 form pairs of nesting arms at opposite ends of the separatin mechanism. The angle section members 43 are coupled by bell cranks 44 to a hydraulic cylinder 45. Means (not shown) are also provided for raising and lowering the arms 35.

As the ladder approaches the station 34 the arms 35 lie between the stiles with their tips below the level of the rungs as shown in full lines in Figure 8. For separating the stiles the tips of the arms 35 are raised to the central plane of the ladder and then, by energising the cylinder 36, moved apart until the stiles are against the upset rung extremities as shown in broken lines in Figure 8.

In this condition the ladder is moved forward towards the rung-fixing station 14 until the first rung is in the region of a second indexing unit 37 similar to the first indexing unit 20. The rung-fixing station 14 has a press (see Figures 9, 10 and 11) comprising two pairs of clamps 38 and, on each side of the ladder, an expanding mandrel 39 and a coining die 41. The clamps 38 are mounted similarly to the clamps 25 and 26 and can be opened and closed vertically by hydraulic or pneumatic cylinders 40. The two pairs of clamps 38 grip the rungs close to the inner walls of the stiles and hold the stiles against the upset rung ends.

The expanding mandrels 39 and coining dies 41 are operated by double-piston hydraulic or pneumatic cylinders 42. An inner ram 46 (forming an inner actuating member) of each cylinder 42 supports the expanding mandrel 39 and a surrounding outer ram 47 (forming an outer actuating member) expands the mandrel 39 and operates the coining die 41. When fluid pressure is applied to the cylinder 42 both rams 46 and 47 move together to enter the expanding mandrel 39 into the bore of the rung end as shown in Figure 11. When the mandrel 39 has been inserted to the required extent its further bodily movement is prevented by a positive stop 48 on the rear end of the ram 46.

The pressure on the cylinder 42, then acts on the outer ram 47 alone to expand the mandrel and to engage the coining die with the rung end.

The expanding mandrel 39 (Figure 11) includes an abutment collar 49, a rubber sleeve 50 and a movable collar 51. The abutment collar 49 is adjustably retained on the end of the inner ram 46. The rubber sleeve 50 and the movable collar 51 are slidable on the ram 46. The coining die 41 is in the form of a flanged collar slidably mounted on guide pins 52 projecting from the front of the outer ram 47 but urged away from that face by annularly spaced compression springs 53. The coining die 41 is also slidable telescopically over the movable collar 51 and the adjacent part of the rubber sleeve 50. When the expanding mandrel 39 reaches the required position inside the rung the coining die 41 is against the rung end but exerts only the force due to compression of the springs 53. As the outer ram 47 continues to advance it bears on the collar 51, compressing the rubber sleeve 50 axially and causing it to expand radially.

The sleeve 50 acts to swell the rung as shown in stage (4) of Figure 1. When the outer ram 47 engages the coining die 41 directly, the force applied through the die 41 to the end of the rung ensures that it is correctly formed and bedded thoroughly against the outer wall of the stile. An adjustable stop 54 (Figure 10) at the rear end of the outer ram 47 is arranged to arrest the outer ram 47 at this stage.

The rung fixing operation as described is carried out rung by rung as the ladder is advanced in steps by the second indexing unit 37. Before each forward indexing stroke, the clamps 38 are opened. The ladder is then moved forward by the second indexing unit 37 and the clamps 38 are closed to grip the next rung. As the fixing of the rungs proceeds, the front end of the ladder moves onto the unloading platform 15 which supports the ladder until completion of the fixing of all the rungs and the removal of the completed ladder from the apparatus.

In the modification of Figures 12 and 13 parts similar to those in Figure 11 have been given the same reference numerals. The rubber sleeve 50 is shorter than the corresponding part in Figure 11. The movable collar at the end next to the outer ram 47 is of larger cross-section than the rung bore and has a tapering portion 55 leading to a spigot 56 of cross-section able to enter the rung bore. When the collar moves to compress the rubber sleeve 50, the tapering portion 55 expands the rung end tightly into the rung hole in the outer wall of the stile. The expanding rubber sleeve 50 swells the rung on each side of the hole in the inner wall of the stile. The coining die 41 forms the rung end against the outer face of the ladder stile as in the previous embodiment.

It is not essential to the invention that the ladder rung be expanded within the hollow stile. The expansion could be confined to the region within the hole in the inner wall of stile and between the stiles close to the inner faces of their inner walls so that the rung is expanded against those faces.

The modification of Figures 14 to 16 concerns the form of upsetting of the rung ends performed at the rung-upsetting station 13. Instead of flaring and then rolling the rung ends outwards as shown at stages (1) and (2) of Figure 1, in this modification the rung ends are folded outwards to form a flange of double thickness. To produce this punches 60 each having a spigot 61 and a shoulder 62 at right angles to the axis of the punch 60 replace the punches 30 of the rung-upsetting station 13.

When the clamps 25 close on the rung the extremities of the rung are left projecting as shown in Figure 14. The spigot 61 of each punch enters the end of the rung bore and the shoulder 62 bears on the extremity of the rung facing it to fold outwards as shown in Figure 15. The spigot 61 prevents the rung material from folding inwards. Movement of the punch 60 continues until the fold is completely flattened against the outer face of the clamps 25 producing a flange of double thickness 63 as shown in Figure 16.

To produce this modified upsetting of the rung ends, the two stages (1) and (2) of Figure 1 are not necessary and punches corresponding to punches 31 of Figure 4 can be omitted. If provided however they may be of final finishing form to ensure that the flanges 63 are properly shaped and completely flattened. The final form of rung fixing produced by the combination of the two modifications of Figures 12 to 16 is shown in Figure 17. It has also been found that with these combined modifications the coining operation of the rung-fixing station 14 are unnecessary and the coining dies 41 may be omitted.

WHAT WE CLAIM IS: 1. A method of making ladders of the kind described which comprises putting the two ladder stiles close together side-by-side, passing the rungs through the holes in both stiles so that they project from the stiles, upsetting the extremities of the rungs, separating the stiles so that they abut the upset extremities and expanding the end portions of the rungs within the hollow stiles and/or against the inner faces of the inner walls of the stiles.

2. A method of making ladders according to claim 1 wherein for holding the rungs while the rung ends are upset a pair of clamps is provided to grip each rung between the extremity and the adjacent stile but leaving the extremity projecting.

3. A method of making ladders according to claim 1 or claim 2 wherein each extremity of the rungs is upset by folding it outwards to form a flange of double thick ness.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

includes an abutment collar 49, a rubber sleeve 50 and a movable collar 51. The abutment collar 49 is adjustably retained on the end of the inner ram 46. The rubber sleeve 50 and the movable collar 51 are slidable on the ram 46. The coining die 41 is in the form of a flanged collar slidably mounted on guide pins 52 projecting from the front of the outer ram 47 but urged away from that face by annularly spaced compression springs 53. The coining die 41 is also slidable telescopically over the movable collar 51 and the adjacent part of the rubber sleeve 50. When the expanding mandrel 39 reaches the required position inside the rung the coining die 41 is against the rung end but exerts only the force due to compression of the springs 53. As the outer ram 47 continues to advance it bears on the collar 51, compressing the rubber sleeve 50 axially and causing it to expand radially.

The sleeve 50 acts to swell the rung as shown in stage (4) of Figure 1. When the outer ram 47 engages the coining die 41 directly, the force applied through the die 41 to the end of the rung ensures that it is correctly formed and bedded thoroughly against the outer wall of the stile. An adjustable stop 54 (Figure 10) at the rear end of the outer ram 47 is arranged to arrest the outer ram 47 at this stage.

The rung fixing operation as described is carried out rung by rung as the ladder is advanced in steps by the second indexing unit 37. Before each forward indexing stroke, the clamps 38 are opened. The ladder is then moved forward by the second indexing unit

37 and the clamps 38 are closed to grip the next rung. As the fixing of the rungs proceeds, the front end of the ladder moves onto the unloading platform 15 which supports the ladder until completion of the fixing of all the rungs and the removal of the completed ladder from the apparatus.

In the modification of Figures 12 and 13 parts similar to those in Figure 11 have been given the same reference numerals. The rubber sleeve 50 is shorter than the corresponding part in Figure 11. The movable collar at the end next to the outer ram 47 is of larger cross-section than the rung bore and has a tapering portion 55 leading to a spigot 56 of cross-section able to enter the rung bore. When the collar moves to compress the rubber sleeve 50, the tapering portion 55 expands the rung end tightly into the rung hole in the outer wall of the stile. The expanding rubber sleeve 50 swells the rung on each side of the hole in the inner wall of the stile. The coining die 41 forms the rung end against the outer face of the ladder stile as in the previous embodiment.

It is not essential to the invention that the ladder rung be expanded within the hollow stile. The expansion could be confined to the region within the hole in the inner wall of stile and between the stiles close to the inner faces of their inner walls so that the rung is expanded against those faces.

The modification of Figures 14 to 16 concerns the form of upsetting of the rung ends performed at the rung-upsetting station 13. Instead of flaring and then rolling the rung ends outwards as shown at stages (1) and (2) of Figure 1, in this modification the rung ends are folded outwards to form a flange of double thickness. To produce this punches 60 each having a spigot 61 and a shoulder 62 at right angles to the axis of the punch 60 replace the punches 30 of the rung-upsetting station 13.

When the clamps 25 close on the rung the extremities of the rung are left projecting as shown in Figure 14. The spigot 61 of each punch enters the end of the rung bore and the shoulder 62 bears on the extremity of the rung facing it to fold outwards as shown in Figure 15. The spigot 61 prevents the rung material from folding inwards. Movement of the punch 60 continues until the fold is completely flattened against the outer face of the clamps 25 producing a flange of double thickness 63 as shown in Figure 16.

To produce this modified upsetting of the rung ends, the two stages (1) and (2) of Figure 1 are not necessary and punches corresponding to punches 31 of Figure 4 can be omitted. If provided however they may be of final finishing form to ensure that the flanges 63 are properly shaped and completely flattened. The final form of rung fixing produced by the combination of the two modifications of Figures 12 to 16 is shown in Figure 17. It has also been found that with these combined modifications the coining operation of the rung-fixing station 14 are unnecessary and the coining dies 41 may be omitted.

WHAT WE CLAIM IS: 1. A method of making ladders of the kind described which comprises putting the two ladder stiles close together side-by-side, passing the rungs through the holes in both stiles so that they project from the stiles, upsetting the extremities of the rungs, separating the stiles so that they abut the upset extremities and expanding the end portions of the rungs within the hollow stiles and/or against the inner faces of the inner walls of the stiles.
2. A method of making ladders according to claim 1 wherein for holding the rungs while the rung ends are upset a pair of clamps is provided to grip each rung between the extremity and the adjacent stile but leaving the extremity projecting.
3. A method of making ladders according to claim 1 or claim 2 wherein each extremity of the rungs is upset by folding it outwards to form a flange of double thick ness.
4. A method of making ladders accord

ing to claim 1 or claim 2 wherein an axially movable punch or each of a succession of axially movable punches is provided to bear on each extremity of the rungs and upset it.
5. A method of making ladders according to claim 4 wherein there are two punches which act in succession, the first punch being shaped simply to flare the rung end; the second punch completing the turning over of the extremity.
6. A method of making ladders according to claim 4 or claim 5 wherein a complementary die part is provided to co-operate with the punch or with each punch.
7. A method of making ladders according to claims 2 and 6 wherein the die part is formed on the adjacent pair of clamps.
8. A method of making ladders according to any preceding claim wherein the upsetting of the extremities of the rungs is done in two or more stages performed simultaneously on adjacent rungs, the ladder being moved along rung by rung to enable all the upsetting operations to be performed on each rung in turn.
9. A method of making ladders according to claim 3 wherein a shouldered punch having a spigot complementary to the bore of the extremity of the rung acts upon the extremity of the rung, the spigot entering the bore of the rung and the shoulder bearing on the end face of the extremity to collapse the extremity of the rung in an outward fold.
10. A method of making ladders according to claim 3 or claim 9 as dependent from claim 2 wherein the extremity of the rung is folded against the adjacent pair of clamps.
11. A method of making ladders according to any of the preceding claims wherein both extremities of each rung are upset simultaneously.
12. A method of making ladders according to any preceding claim wherein the ladder stiles are separated by means including members arranged in pairs spaced apart along the length of the ladder, the members lying between the stiles when the stiles are close together and the members of each pair being moved apart simultaneously to separate the stiles until the stiles abut the upset extremities.
13. A method of making ladders according to any preceding claim wherein the end portions of the rungs are expanded by means of an expanding mandrel inserted in the rung ends.
14. A method of making ladders according to claim 13 wherein the expanding mandrel comprises an elastomeric sleeve whieh expands radially on being compressed axially.
15. A method of making ladders according to claim 14 wherein the elastomeric sleeve is mounted on the inner of co-axial actuating members between an abutment collar secured to the inner actuating member and an axially movable collar also mounted on the inner actuating member, the actuating members being moved together to insert the expanding mandrel in each rung end and then relatively in an axial direction one with respect to the other so that the outer actuating member acts on the movable collar to compress the elastomeric sleeve axially between the movable and abutment collars.
16. A method of making ladders according to any of preceding claims 13 to 15 wherein the expanding mandrel includes a rigid tapering portion which enters and expands the outer extremity of each rung tightly in the hole in the outer wall of the stile.
17. A method of making ladders according to claims 15 and 16 wherein the tapering portion is on the movable collar.
18. A method of making ladders according to any of preceding claims 13 to 17 wherein the expanding mandrel expands the end portion of the rung to grip the hole in the inner wall of the stile and to swell the rung end portion on each side of the inner wall.
19. A method of making ladders according to any preceding claim wherein after the expansion of the end portion of each rung the upset rung extremity is pressed endwise, in a coining operation, against the outer wall of the stile.
20. A method of making ladders according to claims 15 and 19 wherein the coining operation is performed by a coining die around the expanding mandrel and movable axially with respect thereto, the outer actuating member acting on the coining die to perform the coining operation.
21. A method of making ladders according to claim 19 or claim 20 wherein while the end portion of the rung end is being expanded the rung is held by clamps which also serve to support the stile against the endwise pressure applied to the upset rung extremity during the coining operation.
22. Apparatus for making ladders by the method of any one of the preceding claims from pre-assemblies of rungs and hollow stiles, each pre-assembly comprising two stiles and rungs engaging holes in the stiles, the apparatus comprising means for locating the stiles close together side-by-side with the rungs projecting from the stiles, means for upsetting the extremities of the rungs, means for separating the stiles so that they abut the upset extremities and means for expanding the end portion of the rungs within the hollow stiles and/or against the inner faces of the inner walls of the stiles.
23. Apparatus according to claim 22 comprising a loading platform to receive the pre-assemblies fed to the apparatus and at one end of an assembly line of the apparatus; and, in turn along the line, a rung-upsetting station including the said means for upsetting the extremities of the rungs, a stile separating station including the said means for separating the stiles, a rung-fixing station including the said means for expanding the end portions of the rung and an unloading platform.
24. Apparatus for making ladders substantially as described herein with reference to and as illustrated by Figures 4 to 11 of the accompanying drawings.
25. Apparatus for making ladders substantially as described herein with reference to and as illustrated by Figures 4 to 11 as modified by Figures 12 and 13 of the accompanying drawings.
26. Apparatus for making ladders substantially as described herein with reference to and as illustrated by Figures 4 to 11 as modified by Figures 14 to 16 of the accompanying drawings.
27. A method of making ladders substantially as herein described.
28. A ladder made by the method or apparatus according to any preceding claim.
29.' A ladder according to claim 28 and substantially as described herein with reference to and as illustrated by Figure 17 of the accompanying drawings.