GB2282111A

GB2282111A - Lift axles

Info

Publication number: GB2282111A
Application number: GB9319809A
Authority: GB
Inventors: Anthony Arthur Varndell
Original assignee: M & G Tankers & Trailers Ltd
Current assignee: M & G Tankers & Trailers Ltd
Priority date: 1993-09-24
Filing date: 1993-09-24
Publication date: 1995-03-29
Also published as: GB9319809D0

Abstract

At least one axle 2A of a trailer can be lifted even when there is a load on the trailer for a predetermined short period of time to allow the trailer to be manoeuvred in a tight space so reducing the wear which would otherwise take place on the wheels of the lifted axle. <IMAGE>

Description

TRAILER WITH AIR SUSPENSION SYSTEM The invention relates to trailers with air suspension systems. Such trailers can be trailers or semi-trailer units and comprise a chassis having axles with road wheels above which is a cargo compartment including a load carrying platform. Such a trailer usually has a number of transverse axles having road wheels. For example, three axles may be present to allow the trailer to carry the legally authorised maximum weight. An air spring suspension unit is associated with each axle in the form of an air bag adjacent each wheel. Controls are present to control the supply of pressurised air to the bags, and to exhaust, as required.

When the trailer is laden and the vehicle first moves off there is a tendency for the tyres of wheels carrying the load to be eroded because of the high frictional contact between the wheels and the substrate. The wear can remove the tyre tread and the tyre side wall. This problem is particularly severe when the trailer is manoeuvred in a restricted area, e.g. a loading bay or marshalling yard of a freight depot. A large amount of material can be removed from the tyre with an intolerable reduction in its useful life.

It is one object of this invention to provide a device which reduces or eliminates such unacceptable abrasion of the tyres of a laden vehicle by raising at least one axle for a predetermined time period.

According to the invention in one aspect there is provided a device for use with a trailer having load axles and air springs therefor in which the trailer platform is moved relative to the axle by the supply and removal of pressurised air into and out of the air springs, the device being arranged to deflate air springs to remove load from the respective axle so that the axle may be lifted and to direct pressurised air to a reservoir for a predetermined time period whereby the level of frictional contact between the wheels associated with the respective axle and the substrate is reduced during that time period, and then lower the axle.

The timing device is preferably electrically and/or pneumatically controlled under manual operation. Control buttons may be provided on a control box panel and/or may be in the form of a rocker switch present on the dashboard in the drivers cab, e.g. the tractor.

Preferably the device comprises a subcircuit to raise and lower the axle and another to ensure that the device is inactive until there is a load on the bogie.

In a more specific aspect the invention provides: a trailer or semi-trailer having a plurality of axles, each having air spring suspension units associated therewith; an electrically powered device for raising selected axle for a predetermined time period, the device comprising; a switch arranged to be energised when there is a load on the trailer; a manually controlled button arranged to cause the air springs associated with the axle to be exhausted and to actuate a valve to actuate a supplementary air spring to cause the axle to be lifted, and divert pressurised air into a receiver therefor for the predetermined time period and then to release pressurised air from the receiver to the valve to deactivate the supplementary air spring.

In order that the invention may be well understood it will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a plan view of a subframe of the rear part of a semi-trailer; Figure 2 is a circuit diagram of a device of the invention.

As shown in Figure 1, a semi-trailer unit 1 includes three transverse axles 2A, 2B, 2C each having respective wheels 3A, 3B 3C at each end. An air spring suspension unit 4A, 4B, 4C is associated with each respective wheel. Pipelines 5 are connected to each bag on each side of the trailer to draw pressurised air from a reservoir, not shown, and the pipelines are in communication with a height level valve 6 arranged to distribute pressured air between the six bags according to the load on the bogie. As shown, a supplementary air suspension spring bag 10 is present in front of the leading axle 2A. Control valves 7 are present in the pipeline 5 to isolate the air bags 4A when required. The bag 10 is controlled by controls associated with a control box 11, as will be described in relation to Figure 2.

The circuit diagram comprises two sub circuits, one actuation circuit to actuate the bag 10 to raise the leading axle 2A for a predetermined time period and the other a control circuit to energise the lifting means so that such actuation will only take place when there is a load on the bogie.

The control circuit includes a spring biased pressure sensitive pneumatic valve 12 incorporating a non-return valve 13 and connected to the air suspension line 14 containing pressurised air and in communication with the line 5. The pressure in valve 12 builds up according to load on the platform. The valve is connected to a pressure actuated switch 15 (which is shown in the open condition). The switch 15 is in circuit with an 24V electrical supply 16 and a negative return line 17 and is connected to an ON/OFF manual button 18 and a manoeuvre rocker button 19.

The switch 15 has two conditions open and closed and moves to the closed condition when the pressure is released by the valve 12. The ON/OFF button 18 is mounted on the box 11 and the rocker switch 19 is present in the drivers cab.

Each button 18, 19 is connected to a solenoid operated spring return 5 port 2 way pilot valve 20, 21 respectively. These are in circuit with a 5 port 2 way memory valve 22 the output of which leads to both a lifting valve 23 and to a timer 24 comprising a pneumatic time delay relay. This timer device may take a variety of forms and in a preferred form comprises a series of chambers through which pressurised air is passed. The inlet and outlet orifices of the device may be adjusted to control the speed of passage of air through the device, say from between 0 and 60 seconds. The output from the lifting valve 23 is connected to the air supply line to the supplementary bag 10 via line 25. The output from the timer leads to the memory valve 22. The valve 23 also receives supply air from line 26 and is connected to an exhaust line 27 including a check valve 28.

In use, pressurised air is passed via the valve 12 to the switch 15 to trigger the switch to the closed condition when the bogie is loaded. All the air springs 4A, 4B, 4C are inflated.

When the driver wishes to manoeuvre and raise the axle 2A, he presses either button 18 or 19. Pressurised air passes to the respective pilot valve 20, 21 and to the valve 22. This passes a pulse of air to the valve 23 to exhaust the bags 4A and lift the axle 2A. Air emerges as a pulsed output to the second chamber of the valve 22. The air then exhausts from the valves 20, 21 and 23. The axle 2A is then lowered and the air springs 4A are inflated from the pipeline 5 under control of the height valve 6.

As a result of the device of the invention the driver may manoeuvre his laden trailer even in tight spaces with little or no risk that friction between the wheel tyres of the lifted axle and the substrate will abrade or erode the tyre surface. The device of the invention is actuated using a simple control switch conveniently piaced for the driver. After manoeuvre the device will automatically lower the axle to restore the wheels to the correct road contacting position. The device may be actuated more than once when extra manoeuvring is required. The device may be applied to any appropriate axle, not just the leading one. In addition the device may be arranged to be activated when the driver engages a gear, for example, the reverse gear.

Another advantage of the use of the invention is that when the driver manoeuvres the trailer with the axle lifted extra load is applied to the other axle or axles giving improved traction.

Claims

1. A device for use with a trailer having load axles and air springs therefor in which the trailer platform is moved relative to the axle by the supply and removal of pressurised air into and out of the air springs, the device being arranged to deflate air springs to remove load from the respective axle so that the axle may be lifted and to direct pressurised air to a reservoir for a predetermined time period whereby the level of frictional contact between the wheels associated with the respective axle and the substrate is reduced during that time period, and then lower the axle.

2. A device according to Claim 1, which is electrically and/or pneumatically controlled under manual operation.

3. A device according to Claim 2, included control buttons on a control box panel and/or a rocker switch present on the dashboard in the drivers cab.

4. A device according to any preceding Claim, including one subcircuit to raise and lower the axle and another subcircuit to ensure that the device is inactive until there is a load on the bogie.

5. A trailer or semi-trailer having a plurality of axles, each having air spring suspension units associated therewith, and an electrically powered device for raising selected axle for a predetermined time period, the device comprising a switch arranged to be energised when there is a load on the trailer; and a manually controlled button arranged to cause the air springs associated with the axle to be exhausted and to actuate a valve to actuate a supplementary air spring to cause the axle to be lifted, and divert pressurised air into a receiver therefor for the predetermined time period and then to release pressurised air from the receiver to the valve to deactivate the supplementary air spring.

6. A control device or a trailer including such a control device for lifting an axle, substantially as described and with reference to the accompanying drawings.