GB2165326A - Parking brake system for trailers - Google Patents

Abstract

The system comprises a pin 9 which is slidably mounted in a housing 8, so as to be engageable with holes 6 in or abutments 7 on a wheel hub 4 to prevent rotation thereof. A handbrake lever 16 is connected to the pin via brake wires 11, 15 and in its OFF position withdraws pin 9 when lever 16 is moved to its ON position, a compression spring 10 urges the pin 9 towards the wheel hub 4, whereby it engages in one of the holes 6 or one of abutments 7. The housing 8 is mounted on the lever edge of a suspension arm 3. Lever 16 also operates via a further brake wire 11 on a pin of as identical wheel hub arrangement opposite the arrangement illustrated or there may be a respective lever for each arrangement to allow trailer to be manhandled. Securing means incorporating a key may be provided for securing lever 16 in the ON position. <IMAGE>

Description

SPECIFICATION Parking brakes for trailers This invention relates to parking brakes for use with trailers.

Present day regulations concerning the braking requirements for light trailers are such that, quite often, it is permissible for trailers having a gross weight of up to 750Kg to be used without a service brake facility. Generally, unless a trailer is fitted with a service brake facility (e.g. overrun brakes), there is no means of permitting the trailer to be parked safely, which is of special relevance when parking on an incline.

In the past, when it has been decided that a parking brake system has been necessary for safety reasons, then there has been adopted the relatively expensive option of fitting a full service brake system. Thus, the service brake has often been surplus to requirements, and has also caused problems-e.g., when it is wanted to reverse the trailer. A cheap alternative option which is often used is simply to use wheel chocks. However, it will be appreciated that this if far from reliable, as the chocks may not always be kept with the trailer, they may become lost or stolen, or they may simply prove inadequate.

Preferred embodiments of the present invention aim to provide an adequate parking brake system for a light trailer, which is relatively simple and inexpensive, both to manufacture and to install. In this context, a light trailer is regarded as one which is not required by local law to have a service brake.

According to a first aspect of the present invention, there is provided a trailer having a parking brake system which comprises: a first locking part provided on a wheel hub of the trailer, for rotation therewith; a second locking part provided on the trailer; and actuator means for selectively engaging and disengaging the first and second locking parts such that, when engaged, said second part obstructs the path of said first part, thereby to prevent rotation of the respective wheel hub and, when disengaged, said second part does not so obstruct said path, thereby to permit rotation of the respective wheel hub.

Said first part may be a discrete component which is secured to said hub. Alternatively, it may be formed integrally with said hub.

Preferably, said second part is provided on a suspension unit of the respective wheel hub.

Preferably, one of said locking parts comprises a recess and the other of said locking parts comprises a projection adapted to engage said recess. Said first and second parts may comprise said recess and said pin, respectively. Said projection may comprise a pin which is adapted to engage and disengage said recess by respective movement between said locking parts, longitudinally of said pin.

Said pin preferably extends normally of said hub.

The actuator preferably comprises resilient means for resiliently biasing said locking parts towards mutual engagement and/or disengagement. Where said locking parts comprise a pin and a recess, said resilient means may comprise a spring which biases said pin towards said recess.

The actuator means preferably comprises a handbrake lever and a linkage connecting the lever to said second locking part. There may advantageously be provided security means which has a key and is adapted to secure the actuator means in a position in which said first and second locking parts are engaged.

Preferably, the trailer comprises a pair of opposite wheel hubs, each of which is provided with respective first and second locking parts as aforesaid, arranged to be engaged and disengaged by actuator means as aforesaid.

Advantageously, a respective said actuator means may be provided for each of said pair of wheel hubs, such that each of said hubs may be selectively braked, independently of the other. With such a facility, a trailer may be manhandled into position or up an incline, by alternately locking opposite hubs and pivoting the trailer about the locked hub.

In a second aspect, the invention provides a parking brake system of a trailer in accordance with the first aspect of the invention.

In a third aspect, the invention provides a method of modifying a trailer, comprising the steps of fitting to the trailer a parking brake system in accordance with the second aspects of the invention.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawing, the single figure of which illustrates a parking brake system for use with a trailer.

The illustrated parking brake system 1 is for use with a light trailer, for example, of up to 750Kg gross weight, which is otherwise unbraked.

A suspension unit 2 comprises a suspension arm 3, on which a wheel hub 4 is pivotally mounted at 5. In the illustrated example, the wheel hub 4 is formed with four holes 6, at 90" intervals. Between each pair of holes 6 there is formed on the wheel hub 4 a pair of radially extending abutments 7.

Mounted on the lower edge of the suspension arm 3 is a housing 8, in which a pin 9 is slidably mounted. A compression spring 10 disposed within the housing 8 serves to resiliently bias the pin 9 towards the wheel hub 4, to which it is disposed normally. To an inner end of the pin 9 there is connected a brake wire 11. The brake wire extends around a pulley 12 via a guide plate 13 of a clevis joint 14, and is connected at its opposite end to the pin of an identical wheel hub arrangement (not shown) which is disposed opposite the wheel hub arrangement that is illustrated. The clevis joint 14 is connected via a further brake wire 15 to one end of a handbrake lever 16, which in turn is mounted for pivotal movement in a respective housing 17, which is adapted to be secured to a respective trailer.

In use, the suspension unit 2 is secured to a respective trailer, and a wheel is mounted on the hub 4. (An identical arrangement is, of course, fitted at the opposite side of the trailer). The handbrake lever 16 is secured, by means of its mounting 17, at the forward end of the trailer. The brake wires 11, 15 are connected as shown, and appropriately tensioned.

With the handbrake lever 16 in the "OFF" position, as illustrated, the pin 9 is withdrawn away from the wheel hub 4, against the force of the compression spring 10, and the wheel hub 4 is free to rotate. When it is desired to park the trailer, the handbrake lever 16 is moved into its "ON" position, which allows the pin 9 to slide towards the wheel hub 4, under the influence of the compression spring 10. The pin 9 then engages in one of the holes 6, thereby to prevent rotation of the wheel hub 4. If the pin 9 is not initially opposite one of the holes 6, then a small amount of rotation of the wheel hub 4 may take place, until the pin 9 engages a respective one of the holes 6.

It will be appreciated that any suitable cooperating abutment means may be provided between the suspension arm 3 and the wheel hub 4, to prevent rotation of the wheel hub 4 when the parking brake is applied. Thus, for example, in the illustrated arrangement, the pin 9 may alternatively engage any one of the abutments 7. Abutments such as 7 may be arranged to guide the pin 9 into engagement with the holes 6, upon rotation of the hub 4.

There may thus be provided a simple, inexpensive but effective parking brake for a light trailer.

In the illustrated system 1, the "ON" position of the handbrake lever 16 is defined by one end of a slot 18 through which the handbrake lever 16 travels. The "OFF" position of the handbrake lever 16 is defined by a notch at the opposite end of the slot 18. For improved security, there may be provided means for securing the handbrake lever in its "ON" position. Preferably, this securing means incorporates a key, such that the trailer may safely be left unattended. In this context, the term "key" is to be understood to include any suitable security arrangement such as, for example, a combination lock.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification and/or drawings.

Claims (20)

1. A trailer having a parking brake system which comprises: a first locking part provided on a wheel hub of the trailer, for rotation therewith; a second locking part provided on the trailer; and actuator means for selectively engaging and disengaging the first and second locking parts such that, when engaged, said second part obstructs the path of said first part, thereby to prevent rotation of the respective wheel hub and, when disengaged, said second part does not so obstruct said path, thereby to permit rotation of the respective wheel hub.

2. A trailer according to Claim 1, wherein said first part is a discrete component which is secured to said hub.

3. A trailer according to Claim 1, wherein said first part is formed integrally with said hub.

4. A trailer according to Claim 1, 2 or 3, wherein said second part is provided on a suspension unit of the respective wheel hub.

5. A trailer according to any preceding claim, wherein one of said locking parts comprises a recess and the other of said locking parts comprises a projection adapted to engage said recess.

6. A trailer according to Claim 5, wherein said first and second parts comprise said recess and said pin, respectively.

7. A trailer according to Claim 5 or 6, wherein said projection comprises a pin adapted to engage and disengage said recess by respective movement between said locking parts, longitudinally of said pin.

8. A trailer according to Claim 7, wherein said pin extends normally of said hub.

9. A trailer according to any preceding claim, wherein said actuator comprises resilient means for resiliently biasing said locking parts towards mutual engagement and/or disengagement.

10. A trailer according to Claim 9 as appendant to Claim 7 or 8, wherein said resilient means comprises a spring which biasses said pin towards said recess.

11. A trailer according to any preceding claim, wherein said actuator means comprises a handbrake lever and a linkage connecting the lever to said second locking part.

12. A trailer according to any preceding claim, including security means having a key and adapted to secure the actuator means in a position in which said first and second locking parts are engaged.

13. A trailer according to any preceding claim, comprising a pair of opposite wheel hubs, each of which is provided with respective first and second locking parts as aforesaid, arranged to be engaged and disengaged by actuator means as aforesaid.

14. A trailer according to Claim 13, wherein a respective said actuator means is provided for each of said pair of wheel hubs, such that each of said hubs may be selectively braked, independently of the other.

15. A trailer according to any preceding claim, having a gross weight of up to 750Kg.

16. A trailer according to any preceding claim, which is not required by local law to have a service brake.

17. A parking brake system for a trailer, substantially as hereinbefore described with reference to the accompanying drawings.

18. A trailer having a parking brake system according to Claim 17.

19. A parking brake system as recited in any one of Claims 1 to 14.

20. A method of modifying a trailer, comprising the steps of fitting to the trailer a parking brake system according to Claim 19.