WO1999054178A2

WO1999054178A2 - Landing legs for trailers

Info

Publication number: WO1999054178A2
Application number: PCT/ZA1999/000018
Authority: WO
Inventors: Wynand Jacobus Theron
Original assignee: Chapman, Neil, Anthony
Priority date: 1998-04-21
Filing date: 1999-04-21
Publication date: 1999-10-28
Also published as: WO1999054178A3; AU4871699A

Abstract

A landing leg (10) is disclosed which includes telescopic upper and lower parts. Within the upper part (12) there is a drive system (26, 28, 30, 32, 42, 44). This system transmits drive either from a manual handle fitted to a shaft (18) or from a gearbox and motor combination (48) to a crown wheel which is mounted on a vertical shaft. Rotation to the vertical shaft is converted to vertical movement of the lower leg part.

Description

LANDING LEGS FOR TRAILERS

FIELD OF THE INVENTION

THIS INVENTION relates to landing legs for trailers.

BACKGROUND TO THE INVENTION

Trailers drawn by mechanical horses or tractors are widely used in the

transport industry. The horse has at the rear end thereof what is referred to as the

fifth wheel and it is on this that the trailer is supported.

Before the horse is uncoupled from the trailer, the front end of the

trailer must be supported. This is done by winding down landing legs that are

provided at the front of the trailer. Each leg comprises an upper part of hollow

construction which is mounted on the trailer and a lower part which moves

telescopically within the upper part. The upper part of the leg further includes a

drive shaft to which a handle can be fitted. The drive shaft forms the input to a gear

train. The gear train, in some constructions, drives a pinion which meshes with a

rack that is secured to the lower part of the leg. Alternatively, the gear train can

drive a screw which meshes with a non-rotatable nut which is fast with the lower leg

part. In both forms winding of the handle manually raises or lowers the lower leg

part with respect to the upper leg part. Applicant is aware that it has been proposed to replace manually

operated landing legs by landing legs which include an electrical, an hydraulic, or a

pneumatic motor. To the best of Applicant's knowledge these proposals have not

met with great success and the vast majority of landing legs sold are manually

operated.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a

landing leg for supporting the front end of a trailer, the landing leg comprising

telescopic upper and lower parts and means for displacing the lower part up and

down with respect to the upper part, characterized in that said means comprises an

electric motor and gear box combination mounted on the outside of said upper part,

an output shaft of said gear box entering said upper part, there being gearing for

transmitting drive from said shaft to a vertical drive shaft, rotation of said vertical

drive shaft displacing said lower part up and down with respect to the upper part.

According to a further aspect of the present invention there is provided

a landing leg for supporting the front end of a trailer, the landing leg comprising

telescopic upper and lower parts and means for displacing the lower part up and

electric motor and gear box combination mounted on the outside of said upper part, an output shaft of said gear box entering said upper part and having, on the part

thereof which is inside said upper part, a first gear which meshes with a second gear on a transverse shaft which extends across said upper part and is at right angles to

said output shaft, there being gearing for transmitting drive from said second gear to

a vertical drive shaft, rotation of said vertical drive shaft displacing said lower part up

and down with respect to the upper part.

Said second gear can be fast with a sleeve through which said

transverse shaft passes, the sleeve being fast in rotation with said transverse shaft.

The means for rendering said sleeve fast in rotation with said transverse shaft can

be a grub screw.

A further transverse shaft can protrude from said upper part and

include means to which a manual winding handle can be secured.

In a specific constructional form said landing leg includes a further

shaft which is parallel to said transverse shaft and below it, said further shaft

protruding from said upper part and incorporating, on that part which protrudes from

the upper part, means for attaching a windle handle thereto, a first gear wheel which

is fast in rotation with said further shaft, a second gear which is coaxial with said

further shaft but is freely rotatable with respect thereto, third and fourth gear wheels

fast in rotation with said transverse shaft, said first and third gear wheels being in

mesh and said second and fourth gear wheels being in mesh, said fourth gear wheel

being in mesh with a crown wheel which is mounted on said vertical drive shaft. Said gears are preferably bevel gears.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how

the same may be carried into effect, reference will now be made, by way of example,

to the accompanying drawings in which:-

Figure 1 is a pictorial view of a landing leg for a trailer;

Figure 2 is a top plan view of the landing leg with a cap removed; and

Figure 3 diagrammatically illustrates a gear train.

DETAILED DESCRIPTION OF THE DRAWINGS

The landing leg illustrated is generally designated 10 and comprises an

upper cylindrical part 12 of rectangular cross section (see particularly Figure 2) and

a lower part 14 which is of the same cross sectional configuration as the part 12 but

smaller in overall transverse dimensions so that it can slide vertically within the

upper part 12. At the lower end of the lower part 14 there is a ground engaging

plate 16. A cap 19 (Figure 1 ) closes-off the upper end of the upper part 12.

A shaft 18 protrudes horizontally from the upper part 12, there being a

boss 20 welded to the side of the upper part 12 and forming a bearing for an

intermediate zone of the shaft 18. The shaft 18 has a transverse hole 22 which

receives a pin (not shown) for fastening a winding handle (not shown) to the shaft 18.

The shaft 18 extends across the upper part 12. There is a further

bearing 18.1 secured to that wall of the part 12 which is opposed to the wall to which

the boss 20 is secured. The further bearing 18.1 mounts an end of the shaft 18.

Above the shaft 18 there is a further shaft 24 (Figures 2 and 3) which is parallel to

the shaft 18. The mounting of the shaft 24 on the part 12 is diagrammatically shown

at 124 in Figure 1.

A small gear wheel 26 is mounted on the shaft 18 and meshes with a

larger gear wheel 28 fast in rotation with the upper shaft 24. At the other end of the

shaft 24 there is a further small gear wheel 30 which meshes with a larger gear

wheel 32 which is mounted on, but is freely rotatable with respect to, the shaft 18.

The gear wheel 32 meshes with a crown wheel 34 (see Figures 2 and 3) which is

mounted for rotation about a vertical axis coincident with the common centre line of

the upper and lower parts 12 and 14. The crown wheel 34 is mounted on a vertically

extending shaft 36 which, when rotated by the crown wheel 34, raises and lowers

the lower part 14. This can be by means of a worm gear (not shown) on the shaft 36

which co-operates with a rack on the part 14.

The gear wheel 28 protrudes above the top edge of the upper part 12.

The cap 19 which closes off the end of the upper part 12 has a recess in the

underside thereof and a bulge 19.1 in the top thereof for receiving the protruding part of the gear wheel 28.

During manual operation, the handle is used to rotate the shaft 18.

Drive is transmitted through the gear wheels 26 and 28, the shaft 24 and the wheels

30, 32 and 34 to the shaft 36.

On the shaft 24 between the gear wheels 28 and 30 there is a sleeve

38 which is secured by a grub screw 40 to the shaft 24. A bevel gear 42 is integral

with the sleeve 38, or secured to the sleeve 38, so as to be fast in rotation therewith.

The bevel gear 42 meshes with a further bevel gear 44 fast in rotation

with a shaft 46. It will be noted that the gear 42 is larger than the gear 44 so that the

gear 44 rotates more rapidly than the gear 42 when the gears are in motion.

A commercially available electrical motor and gear box combination 48

is mounted externally on one side of the upper part 12.

The motor of the combination 48 is designated 50 and drives a vertical

shaft (not shown) which lies inside a casing 52. The shaft is in the form of a worm

which drives the input gear of the gear box 54 of the combination 48.

The output shaft of the gear box 54 is constituted by the shaft 46 which

passes through the wall of the upper part 12. The combination 48 is secured to the upper part 12 by means of a

mounting ring 56 which is connected to the remainder of the combination 48 by four

struts 58 arranged around the axis of the shaft 46. Studs 70 connect the ring 56 to

the part 12. Two of the studs 70 are shown in Figure 1.

An opening is drilled in the part 12, the opening receiving a bearing 62

through which the shaft 46 passes.

In use of the landing leg the motor 50 drives the vertical worm in the

casing 52, and this in turn drives the gear box 54 and hence the shaft 46. The bevel

gear 44 on the shaft 46 turns the bevel gear 42. Because the bevel gear 42 is fast

with the sleeve 38, and the sleeve 38 is in turn fast with the shaft 24, the smaller

gear wheel 30 is rotated, thus driving the larger gear wheel 32, the crown wheel 34

and the shaft 36. Hence the lower part 14 is raised or lowered depending on the

direction of rotation of the motor.

A bracket (not shown) secured to the side of the motor carries three

control buttons. To operate the landing leg it is necessary to select "up" or "down"

by pressing the appropriate button and then press the "run" button. The motor 50

requires twenty four volts to operate it and the current drawn is such that the wiring

used to feed power to the tail lights or brake lights of the trailer is sufficient to carry

the current drawn. In an alternative construction a pressure operated switch is provided.

When a trailer is connected to a horse, or disconnected from a horse, a brake air

line is connected or disconnected. The pressure pulse which occurs when this

connection is made or broken can be employed so as automatically to power the

motor thereby automatically to raise or lower the leg.

It is also possible to provide a remote control so that the driver does

not have to be immediately adjacent the landing leg to operate it.

Claims

CLAIMS:

1. A landing leg for supporting the front end of a trailer, the landing leg

(10) comprising telescopic upper and lower parts (12, 14) and means for displacing

the lower part (14) up and down with respect to the upper part (12), characterized in

that said means comprises an electric motor and gear box combination (48)

mounted on the outside of said upper part (12), an output shaft (46) of said gear box

(54) entering said upper part (12), there being gearing (30, 32, 34) for transmitting

drive from said shaft (46) to a vertical drive shaft (36), rotation of said vertical drive

shaft (36) displacing said lower part (14) up and down with respect to the upper part

(12).

2. A landing leg for supporting the front end of a trailer, the landing leg

that said means comprises an electric motor and gear box combination (48)

(54) entering said upper part (12) and having, on the part thereof which is inside said

upper part (12), a first gear (44) which meshes with a second gear (42) on a

transverse shaft (24) which extends across said upper part (12) and is at right

angles to said output shaft (46), there being gearing (30, 32, 34) for transmitting

drive from said second gear (42) to a vertical drive shaft (36), rotation of said vertical

drive shaft (36) displacing said lower part (14) up and down with respect to the upper part (12).

3. A landing leg as claimed in claim 2, wherein said second gear (42) is

fast with a sleeve (38) through which said transverse shaft passes, the sleeve being

fast in rotation with said transverse shaft (24).

4. A landing leg as claimed in claim 2 and including a further transverse

shaft (18) which protrudes from said upper part (12) and include means (22) to which a manual winding handle can be secured.

5. A landing leg as claimed in claim 2, and including a further shaft (18)

which is parallel to said transverse shaft (24) and below it, said further shaft (18)

protruding from said upper part (12) and incorporating, on that part which protrudes

from the upper part, means (22) for attaching a windle handle thereto, a first gear

wheel (26) which is fast in rotation with said further shaft (18), a second gear (32)

which is coaxial with said further shaft (18) but is freely rotatable with respect

thereto, third and fourth gear wheels (28, 30) fast in rotation with said transverse

shaft (24), said first and third gear wheels (26, 28) being in mesh and said second

and fourth gear wheels (32, 30) being in mesh, said fourth gear wheel (32) being in

mesh with a crown wheel (34) which is mounted on said vertical drive shaft (36).

6. A landing leg as claimed in claims 2, 3, 4 or 5, wherein said first and

second gears (42, 44) are bevel gears.