Since when did it become a legal obligation for any medium goods vehicle used to take a category C1 driving test to have ABS? Apparently I can't take the test in our lorry because it doesn't have ABS.
Questions:
1. How do you implement ABS on an air-driven braking system, or are small lorries all hydraulic now?
2. Is ABS now a standard fitting in lorries?
3. Does it actually make any difference to controlling the lorry in an emergency stop given the size of the vehicle?
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1/ ABS can work on pneumatics, what proportion of small trucks are hydraulic I dont know.
2/ Dont know.
3/ Undoubtedly.
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1. Air braked systems are still hydraulically operated at the hub. Must be, as my Bedford has a rod clutch, air brakes, and still has two hydraulic fluid reservoirs!
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The van and light truck hire fleet I work on includes a mixture of MAN and Iveco 7.5 tonners. All are less than 3yrs old and all have ABS.
The MAN's are fully air braked - no hydraulics at all.
The Iveco's have a hydraulic footbrake, and it's assisted by compressed air. Compressed air is the only connection between the brake pedal and the hydraulic system.
On each, the park brake is spring operated, held off by compressed air. Both have exhaust brakes.
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Since when did it become a legal obligation for any medium goods vehicle used to take a category C1 driving test to have ABS?
The Motor Vehicles (Driving Licences) (Amendment) (No. 4) Regulations 2003
www.opsi.gov.uk/si/si2003/uksi_20032003_en.pdf
"Regulation 5... provide[s] that the vehicle to be driven by a person submitting himself for a test for a licence authorising the driving of category C, D, C+E, or D+E vehicles (large goods vehicles and passenger-carrying vehicles each with or without a trailer) must be fitted with an anti-lock braking system."
According to the document, Regulation 5 came into force 1st October 2003
1. How do you implement ABS on an air-driven braking system or are small lorries all hydraulic now?
They've been doing in on trains for decades, with no hydraulics at all. Couldn't tell you how, though.
2. Is ABS now a standard fitting in lorries?
The Road Vehicles (Construction and Use) (Amendment) (No. 4) Regulations 2001
www.opsi.gov.uk/si/si2001/uksi_20013208_en.pdf
"Regulation 5 amends regulation 15 of the 1986 Regulations... This has the effect of extending the categories of vehicles which are required to be fitted with ABS at the point of manufacture to include all passenger-carrying vehicles with more than 8 passenger seats in addition to the drivers, all goods vehicles over 3500 kg and all trailers over 3500kg. This extension will apply to all new vehicles of the relevant kinds first used on or after 1st April 2002."
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Mike Farrow
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Sorry, I see you are talking about C1, in which case you may have to disregard most of the above.
More haste less speed.
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Mike Farrow
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In some ways, it's actually easier to implement ABS on air brakes - because you don't need to provide for pumping air back to the master cylinder, whereas with a hydraulic system, you must pump the fluid back - you can't exhaust it to atmosphere!
WSP on trains is a remarkably similar system, except it operates on each wheelset, rather than on each wheel. You can often see the connections and the different bearing covers on the ends of the axles which have the reluctor rings. (If you are the type who looks for that sort of thing!)
WSP on trains is made difficult by the more sudden onset of slip which you get on a wheel / rail system. With cars and trucks, you typically get peak braking force at about 20% slip - after which, the brake force drops off significantly. On a rail wheel, you may get breakaway at 2% slip, but, the brake force doesn't drop off quickly - the characteristic is more flat. This makes it more difficult to differentiate betwen good braking conditions and gross slip. One way this is done on more modern trains is to use a radar system to sense the absolute speed of the train, rather than rely on wheel rotation to estimate it - this enables creep controlled traction and braking, which works brilliantly, but is way too expensive for cars.
Number_Cruncher
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1. Like the other replies have stated, ABS works on pneumatics in very much the same way as hydraulics, in fact the ABS are very similar as their basic principle is to reduce the force being applied to the brake that is detected as being 'locked up'. I think most small lorries (7.5 tonners) have full air brake systems nowadays whereas in the olden days it was quite normal to have 'air over hydraulic' sytems such as local yokel's Bedford has where the air pressure applied by the foot valve is then converted into hydraulic pressure through a master cyclinder before operating the brakes in the conventional hydraulic fashion. In fact the last 7.5 ton trucks that I can remember still using this 'old hat' method of air over hydraulic was the Iveco 75E15 range up until a few years ago.
2. ABS is a fairly standard fitting in lorries now, just as it is in the range of new cars that you can buy. It has been used on the big lorries (such as artics) for quite a number of years and the vast majority of trailers used on the roads today are also ABS equiped. A lot of the bigs trucks also have traction control systems (often referred to as ASR - acceleration skid reduction) which uses some of the ABS components to detect which wheel is loosing traction.
3. I can also conclude that it does make a good difference in stopping the vehicle in an emergency with this technology on board. If you have ever had a truck sliding up the road with its wheels locked then you will know that it is a scary experience. Whereas with ABS fitted it makes the skid more managable although hearing the a wheel lock and the ABS releasing the air pressure to counter-act it every half second can come as a shock.
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