WO2003008257A1 - Safety device for a tractor/trailer unit - Google Patents

Abstract

A safety device for use with a release mechanism of a tractor/trailer unit, includes means movable from a first position to a second position, said means being prevented from moving from said first position to said second position until the braking of the trailer of said tractor/trailer unit is applied. The means is a pin (20) which is movable pneumatically from its first position in which it prevents the release of the release mechanism, to its second position. The safety device is carried by and supported by part of the fifth wheel (8) of a tractor/trailer unit with which the afore-mentioned release mechanism is associated.

Description

SAFETY DEVICE FOR A TRACTOR/TRAILER UNIT

This invention relates to a safety device, and more particularly to a

safety device for use in association with the release mechanism of a

heavy goods vehicle such as a tractor/trailer unit.

A tractor/trailer unit comprises a tractor to provide the motive power

and a detachable trailer in which or on which goods to be conveyed are

carried. The trailer is connected to the tractor through the intermediary

of what is generally termed a 'fifth wheel' which is carried on the

tractor and which is engaged by a substantial pin carried on the trailer.

To enable the pin on the trailer to be released from the fifth wheel and

thereby release the trailer from the tractor, a release mechanism is

provided which is movable from a first position - in which the tractor

and trailer are coupled together so that the tractor may tow the trailer -

to a second position - in which the trailer may be released from the

tractor. A simple pin or bolt may be provided to maintain the release

mechanism in the first position, the pin or bolt being removable to

enable the release mechanism to be operated. Whilst the above-described release mechanism is relatively simple and

easy to operate, there are inherent disadvantages with the arrangement.

The most serious of these disadvantages is that if the pin or bolt which

maintains the release mechanism in its first position is released and the

driver of the unit forgets or omits to apply the brakes to the trailer, then

the trailer can roll away from the tractor, particularly if the tractor/

trailer unit is on an incline. This can, as will be appreciated, have

serious and disastrous consequences.

The present invention therefore seeks to provide a safety device for use

in association with the release mechanism of a tractor/trailer unit

which will obviate the above and other disadvantages.

According to the present invention there is provided a safety device for

use in association with a release mechanism of a tractor/trailer unit,

said device including means movable from a first position to a second

position, said device being prevented from moving from said first

position to said second position until tl e braking of tlie trailer of said tractor/trailer unit is applied.

Preferably, said means will be a pin which is movable from a first

position in which it engages the release mechanism to prevent

operation of said release mechanism, to a second position in which

said release mechanism may be operated.

Said pin will be movable from its first position to its second position

by fluid pressure-operated means, and said pin will preferably be

spring-loaded.

Said pin will preferably carry a piston which is movable with the said

pin so as to cause movement of said pin.

In order that the invention may be more readily understood,

embodiments thereof will now be described, by way of example only,

reference being made to the accompanying drawings, wherein:

Figure 1 is a perspective view of a safety device in accordance with a first embodiment of the invention;

Figure 2 is a sectional elevation through the safety device of Figure 1;

Figure 3 is a perspective view of a fifth wheel of a tractor/trailer unit

and associated release mechanism, part of the fifth wheel being shown

in phantom for the sake of clarity;

Figure 4 is an enlarged perspective view of an alternative arrangement

of part of Figure 3;

Figure 5 is a view similar to Figure 2, but showing a second

embodiment of the invention; and

Figure 6 is a perspective view of part of Figure 5.

Referring to the drawings, and firstly to Figure 1, there is shown a

safety device indicated generally by reference numeral 2 which is

carried by and supported by a bracket 4 secured - as seen in Figure 3 -

to a back wall 6 of a fifth wheel 8 of a tractor (not shown) forming a

part of a tractor/trailer unit, not shown. For the sake of clarity, the

safety device is not shown in Figure 3. The safety device 2, referring now to both Figures 1 and 2, comprises

an upper body 10 and a lower body 12, the upper body 10 having an

internally threaded portion 14 and the lower body having an external

threaded portion 16 so that the two bodies may be removably secured

together. The lower body 12 is generally hexagonal (see Figure 1) in

shape in order that it may be engaged by a spanner or other suitable

tool or appliance for ease of maintenance of the device. A nylon seal

18 is provided between the two bodies.

Located within the two bodies 10 and 12, and projectable from the top

of the upper body 10, is a pin 20 which passes through a sleeve

bearing 22, means (not shown) being provided to prevent the pin

rotating on its axis relative to the sleeve bearing 22. This ensures that

the pin will always be in the correct position for proper operation. A

nylon seal 24 is held in position by a nut 26, the nut being removable

for replacing the seal as and when necessary.

The pin 20 includes a piston 28 which is movable vertically (in the drawing) by the amount indicated by arrow 'A', a nylon seal 30 being

provided in the lower body 12, the purpose of which will be explained

hereinafter. The pin 20 is spring-loaded by means of a spring 32, and a

buffer 34 is provided in the lower body 12 to limit the downward

movement of the pin 20 when the pin is moving to its inoperative

position as will be later explained.

The upper body 10 has an air connection 36, and the lower body 12

has a vent 38 in order that the chamber 12A of the lower body can

remain at zero pressure to prevent inadvertent raising of the pin 20

within the air chamber 10A of the upper body 10.

Referring now to Figure 3, the fifth wheel 8 has associated therewith a

release mechanism consisting of a first arm 40 and a second arm 42,

the arms 40 and 42 being pivotally linked together at pivot pint 44 so

that said arms may move relative to one another. As will be seen, the

arm 40 passes through an opening 46 in the body of the fifth wheel,

and the arm 42 passes through an opening 48 in the back wall 6 of said fifth wheel. The arm 40 passes over and rest on an upper section 4A

of the bracket 4, has a through-hole 50 therein, and includes a handle

52 by which the release mechanism may be moved relative to the fifth

wheel 8. The upper section 4 A of the bracket 4 has a through-hole 4B

therein.

In operation, and assuming the pin 20 to be in the position shown in

Figures 1 and 2, i.e. in its raised position with the trailer coupled to the

tractor, the pin 20 - in its raised position - will project upwardly

through the nut 26 and through the hole 50 in the arm 40. In this

position of the pin, the release mechanism associated with the fifth

wheel cannot be operated and the trailer will remain locked to the

tractor. When it is required to release the trailer from the tractor, the

air line (not shown) running from the tractor to the brakes of the trailer

through the intermediary of a coupling, is uncoupled by releasing the

coupling which has the effect of applying the brakes of the trailer. One

part of the said coupling is then coupled to the air connection 36 of the

upper body 10 of the safety device 2. Such coupling pressurises the chamber 10A of the upper body 10, the pressure acting on the

piston 28 so as to move said piston downwardly against the force in

the spring 32. Such movement causes the pin 20 to move downwardly

so that it leaves the through-hole 50 in the arm 40 of the release

mechanism. Thus the arm 40 may now be moved by means of the

handle 52 which causes appropriate movement of the arm 42 to release

the substantial pin carried by the trailer from the fifth wheel and so

release the trailer from the tractor. It will be borne in mind that during

the operation of the release mechanism, the brakes are applied to the

trailer such that the trailer cannot move relative to the tractor, the latter

being driven away in order to leave the trailer in situ.

To subsequently couple the trailer to the tractor, the tractor is moved

into position relative to the stationery trailer such that the substantial

pin carried by the trailer is in the appropriate position relative to the

fifth wheel 8. The arm 40 is then moved so as to move the arm 42 and

so couple the trailer to the tractor. During such movement of the arm

40, the through-hole 50 therein will come into coincidence with the through-hole 4B in the upper surface 4A of the bracket 4. The air

coupling is then uncoupled from the air connection 36 which thus

releases the pressure from the chamber 10A so as to allow the pin 20

to move upwardly under the influence of the spring 32 and to pass

through the through-holes 4B and 50 so as to prevent further move¬

ment of the release mechanism. The air coupling is then re-applied to

the brake coupling of the trailer so as to release the brakes of the

trailer.

It will be observed from Figures 1 and 2 that the upper extremity of

the pin 20 is tapered so that during movement of the arm 40 the pin

will retract and then automatically engage in the through-holes

previously referred to .

Referring now to Figure 4, this shows a slight modification to the

arrangement of the arms 40 and 42. It will be seen that in this instance

the arm 42A - instead of the arm 40 A - is provided with a through-hole

54, this through-hole 54 being brought into correspondence with the through-hole 4B in the bracket 4 during movement of the two arms.

Otherwise, the operation of the safety device is as previously

described.

Referring now to Figures 5 and 6, it will be seen that the safety device

comprises a body 100 and end caps 102 and 104. The body 100 is

internally threaded at 106 and 108, and the end caps 102 and 104 are

externally threaded at 110 and 112 respectively in order that the end

caps may be secured to the body 100 so as to form a composite unit,

indicated generally by reference numeral 114. The body 100 has an air

connection 116, and the end cap 104 has a vent 118 which serve the

same purposes as previously described with reference to Figures 1 and

2. The end cap 102 has a through-bore 102A therein, and the end cap

104 has a through-bore 104 A.

Located in the composite unit 114 is a pin 120 which carries a piston

122, the piston incorporating an O-ring seal 124 in order to isolate a

chamber 126 above the piston 122 from a chamber 128 below said piston. The pin 120 is spring-loaded by means of a coil spring 130 in

the chamber 128. The upper end (in the drawing) of the pin 120 is

tapered as indicated at 120A.

A seal 132 is provided between the pin 120 and the end cap 102.

The operation of the safety device of Figures 5 and 6 is the same as

that previously described with reference to the previous embodiment,

such that it is not thought necessary to provide further explanations.

Thus the invention provides a safety device for use in association with

the release mechanism of a fifth wheel of a tractor/trailer unit which

simply and effectively prevents the release of the trailer from the

tractor until the braking is applied to the trailer. The release mechanism

simply cannot be operated until said braking is applied.

The driver of the tractor/trailer unit cannot forget to apply the braking

of the trailer - as very often happens - otherwise the release mechanism cannot be actuated to separate the trailer and tractoT. This has great

significance in that the trailer cannot move relative to the tractor, the

trailer remaining in situ once the pin of the safety device is in

engagement. Thus the trailer cannot roll away from the tractor and so

the many accidents which have occurred in the past will be easily and

readily avoided.

Finally, it will be appreciated that safety devices in accordance with

the invention may be modified in various ways, and it is intended that

any such modifications be included in the appended claims.

Claims

CLALMS:

L A safety device for use in association with a release mechanism

of a tractor/trailer unit including means movable from a first position

to a second position, said device being prevented from moving from

said first position to said second position until the braking of the

trailer of said tractor/trailer unit is applied.

2. A safety device according to Claim 1, wherein said means is a pin

which is movable from a first position in which it engages the release

mechanism to prevent operation of said release mechanism, to a

second position in which said release mechanism may be operated.

3. A safety device according to Claim 2, wherein said pin is

movable from its first position to its second position by fluid pressure-

operated means.

4. A safety device according to Claim 2 or Claim 3, wherein said pin is spring-loaded.

5. A safety device according to any of Claims 2 to 4, wherein said

pin incorporates a piston which is movable with said pin so as to

cause movement of said pin.

6. A safety device according to Claim 2, wherein said device

includes an upper body and a lower body, said bodies being removably

secured together.

7. A safety device according to Claim 6, wherein said pin projects

from said upper body in its second position.

8. A safety device according to Claim 7, wherein in its second

position, the said pin engages an arm forming part of said release

mechanism.

9. A safety device according to Claim 2, wherein means are provided to limit the movement of said between its positions.

10. A safety device according to any of Claims 6 to 9, wherein

said upper body includes an air connection by which the device may be

coupled to an air line of said tractor, and wherein said lower body

includes a vent to prevent inadvertent raising of the pin.

11. A safety device according to Claim 2, wherein said device

includes a body and end caps removably secured to said body so as to

form a composite unit, the said body including an air connection and

one of said end caps including a vent to prevent inadvertent raising of

the pin.

12. A safety device according to any of the preceding Claims,

wherein said safety device is carried by and supported by a bracket

secured to a back wall of a fifth wheel of a tractor/trailer unit, the

release mechanism being associated with said fifth wheel.