Don't flap about with spray suppressants
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The UK will be the first country in Europe to introduce lorry spray suppression — it does so next spring. Putting aside the furore caused by the draft regulations, David Wilcox examines what the operator will need to fit
THERE can surely be nobody who questions the need for reducing the spray thrown up by lorries travelling at speed on wet roads, but how this relatively simple objective is achieved is proving to be a thorny subject.
We have 38-tonners and higher speed limits for lorries so the Government's haste to reduce spray could be seen as a sweetener for the lorry-hating general public as well as a safety measure.
The existing Motor Vehicle (Construction and Use) Regulations 1978 require only that lorries be equipped with "wings or other similar fittings to catch, so far as practicable, mud or water thrown up by the rotation of the wheels unless adequate protection is afforded by the body of the vehicle."
To develop this general aim into specific anti-spray legislation the Department of Transport will amend the C and U regulations and went to the British Standards Insitution to draw up a spray suppression Standard as the basis of the amending regulations.
The DTp published its draft of the amending regulations together with the draft of their underlying BSI Standard (BS AU200 1984) early in March and comments on these proposals have to be with the DTp by next Thursday, April 19.
It is important to stress that both the amending regulations and BSI Standard are only in draft form at the moment; their final form may be slightly different although it is highly unlikely that there will be any radical changes.
Already there has been deep and widespread criticism of the regulations and Standard. Naturally, the two operators' trade associations, the Freight Transport Association and the Road Haulage Association, reserve most of their criticism for the list of vehicles that will have to meet the spray suppression legislation (see table).
In particular they dislike the retrospective .element involved in fitting the equipment to all existing trailers plated for over 16 tonnes and with two or more axles.
It is estimated that around 160,000 existing trailers will need to be fitted. Once that is done the spray suppression market will settle down to an annual level of around 40,000 vehicles of over 7.5 tonnes and 9,000 trailers. In money terms that is reckoned to be a £40m retrofit market plus a stable level of £15m a year thereafter.
Most criticism has been directed at the draft BSI Standard. Operators, trade associations and even the spray suppression product manufacturers have found fault with BS AU200 1984.
The Institute of Road Transport Engineers has been the fiercest critic. It says the draft Standard's minimum proposals will not give a significant reduction in spray, that it ignores fundamental requirements and that it fails to set any objective performance levels for lorry spray suppression.
In short, the IRTE is suspicious of "cornmercial interest motivations".
So where does this leave the operator who will need to fit spray suppression equipment?
As mentioned earlier, it is unlikely that there will be a major rethink at this late state despite the adverse comments. Precise dimensions are many and complex; CM will publish them when the final Standard emerges. In the meantime, here is a guide to the options open to the operator, including the more salient points and critical dimensions.
In its preamble the Standard points out that all the measurements are taken with the vehicle unladen. This, as you will see, is a bone of contention with almost everybody who has reacted to the draft and there is a fighting chance that this could be changed to laden in the final draft.
The Standard also notes that although valances for the inside of the wheel are not compulsory they are recommended whenever possible. To meet the forthcoming spray suppression regulations the Standard recognises three possible methods: (1) Conventional mudguards with the addition of a mudflap made of a spray suppres sion material Most standard mudguards fitted to rigids and tractive units already conform to the Standard's requirements (it calls them wheelguards) as far as their dimensions are • concerned.
The main point to watch is that they are mounted in a position laid down by the Standard which is intended to keep the vertical gap between the tyre and the valance (the outer vertical part of the mudguard) relatively small.
More specifically, for steering axles the radius of the lower edge of the valance must not exceed 1.5 times the radius of the tyre. Taking the most common size 11R22.5 tyre this equates to a maximum gap between valance and tyre when viewed from the side of approximately 260mm (10.2in).
For non-steering axles the factor is reduced to 1.25 times the radius of the tyre, which on the same tyre size example gives a maximum gap of 130mm (5.1in).
On steering axles the distance between the outer edge of the tyre measured in a horizontal plane to the inner edge of the valance must be no more than 100mm. In the case of non-steering axles this must be reduced to 75mm unless the valance comes down to be at least level with the circumference of the tyre — then the gap can be as much as 100mm.
Most standard rigid and tractive unit mud guards satisfy these points and so will need only the addition of a rear mudflap within 300mm of the rearmost point of the tyre. In a close-coupled tandem or triaxle bogie if the gap between tyres is less than 250mm a flap is needed only on the rear tyre.
The mudflap must come down to within 150mm of the ground when the vehicle is unladen. This, says most objectors, is unrealistic because when the vehicle is laden the suspension travel will lead to the flap dragging on the ground.
The same problem could also easily arise with tippers which need greater ground clearance for off-road work.
Similarly, if the valance/tyre vertical gap requirement is met when the vehicle is unla den the mudguard could be fouling the tyre when laden. This can be overcome by extending the valance downwards.
The mudflap (and the valance extension, if needed) must be faced with a spray suppression material and this must run inside the mudguard to at least a point 100mm above the wheel's centre line.
The definition of spray suppression material is absolutely crucial — some products currently on the market under this title will become useless once the spray regulations come into force next year.
(2) Alternative to conventional mudguards for non-steering axles This is primarily catering for trailers that do not have conventional mudguards and are currently operating with just mudflaps.
For these applications the draft Standard requires a combination of a valance and rear flap, both faced with a spray suppression material that satisfies the Standard.
Without going into the details of the dimensions, the salient points are that the valances must be at least 100mm deep and come down at least to a point level with the top of the tyre.
The mudflaps must meet the same ground clearance rule mentioned in (1) and the rules for multi-axle bogies are also the same but the whole flap must be faced with spray suppression material.
(3) Using the Schlegel Cats Whiskers system This is the third and final type of spray suppression catered for in the draft Standard. It is coyly referred to as an air/water separator but is plainly written around the Schlegel product. Conventional mudguards as described in (1) are needed but the vertical gap between tyre and valance is different to allow for the filaments that form the Cats Whiskers running along the lower edge of the valance.
For the steering axle, the radius taken from the tips of the filaments must be no more than 1.05 times the radius of the tyre.
Using the example of a 11R22.5 tyre this gives a maximum gap of 26mm (1n). between the tips of the filaments and the edge of the tyre when viewed from the side.
On non-steered axles the tips of the filaments must come down at least to a point level with the circumference of the tyre.
Spray suppressant mudflaps are still needed. If they are faced with another material such as Monsanto Clear Pass the same mudflap dimensional and mounting requirements as in (1) apply.
Alternatively, the flap can be plain rubber but with a strip of Cat Whiskers along its bottom edge, in which case the tips of the filaments must be within just 120mm of the ground.
Those, rightly or wrongly, are the three routes to cutting spray that are legislated for in the draft Standard. It concludes with a note that improving the vehicle's aerodynamics does help to keep spray closer to the road and hence clear of the driver's eyeline.
The three aerodynamic aids specifically mentioned are a cab roof-mounted air def lector, sideskirts and a splitter vane (or vertical vortex stabiliser) on the front bulkhead of a box trailer. No measurements or standards are set for these.
Spray suppression materials
Whichever of the three methods of spray suppression an operator chooses to use, he will need to fit some spray suppression material, even if it is just for the mudflap as described in (1).
The draft Standard includes a prescribed test method for assessing the effectiveness • of spray suppression material. The product manufacturers carry out the test themselves.
Water is sprayed onto a sample of the material at a controlled rate via a series of jets and the water that drains off the sample is collected and measured. The more water collected theoretically means that less has been emitted as spray and so demonstrates the effectiveness of the material.
To reach the Standard at least 60 per cent of the water sprayed has to be collected by the material.
This test procedure has been roundly slated on the grounds that it is unrealistic and inadequate. Be that as it may, the test method has already shown that some products currently being sold as spray suppressants will not be able to meet the 60 per cent pass mark.
Some claim to comfortably exceed it with results up around 90 per cent but others are down in the 30-50 per cent range. As things stand at the moment, products that fail to meet the Standard help to reduce lorry spray but will be worthless as far as the law is concerned when the regulations come into force next year.
As far as CM can establish at present, these are the only products that can meet the draft Standard for spray suppression material, although we do know of at least one other material currently under field trials with a major operator.
Monsanto, Clear Pass Dept., Thames Tower, Burleys Way, Leicester LE1 3TP.
Clear Pass rain flaps were developed in 1978 in the USA (where they are called Spray Guard) and were launched in the UK in Spring 1980. With this head start on the competition they are market leaders and are fitted to over 10,000 lorries. While the Clear Pass polyethylene bristle surface exceeds the 60 per cent pass mark some of the mounting instructions previously included would be incorrect under the draft Standard; Monsanto is already changing these.
Typical Clear Pass prices for a pre-cut kit of the necessary flaps, valances and fittings: Two axle tractive unit: £90-£110 Two axle rigid: £80-E90 Tandem axle trailer: £135-£160 Close-coupled triaxle trailer: 042 Schlegel (UK), Ring Road, Seacroft, Leeds LS14 1LY Schlegel launched its Cats Whiskers in the UK last year and claim it is the most effective spray suppressor on the market, although admits it is relatively expensive.
Polypropylene filaments are moulded in a bead and held in a shaped aluminium carrier mounted on the edge of the mudguard valance. Cats Whiskers are sold as a kit to fit an individual axle.
Typical prices: Steering axle: £65-£85 Non-steering axle: £50
Netlon, Kelly Street, Blackburn BB2 413.1
Netlon is to launch its spray suppression system early in May; tests on a rig designed in conjunction with the University of Southampton show that the material will comfortably exceed the Standard. The material is a sandwich of three layers of plastic mesh with a reinforced rubber back sheet.
This combination achieves a 68 per cent mark on the prescribed test but a figure of 90 per cent plus is said to be possible if Netlon adds more layers of mesh.
3M (UK), 3M House, PO Box 1, Bracknell, Berks 3M is aiming to launch its spray suppressant material in the summer, with production starting in June/July. The company says it has a non-woven web-type labyrinth construction although most people will say it is like a pot-scourer. This material is not new to 3M — the company makes Scotchbrite scourers — but the commercial vehicle industry is and 3M is currently working on how to distribute the product.
It claims that it can exceed the 60 per cent draft British Standard pass mark with a good margin.
Boydell & Jacks, Wingard House, Lincoln Street, Healey Wood, Burnley BB11 2HW Boydell & Jacks intends to launch its spray supressant at the Institute of Road Transport Engineers exhibition at Solihull on May 17/18. The company already produces the conventional mudguards (Featherwing) and the new product will complement these.
Exactly how the material will work is still a secret but it is said that it can definitely pass the 60 per cent test. The company has revealed that it will be sold as detachable pads that can be easily removed from the mudflaps and valances for washing or replacement. Prices have not been released but Boydell & Jacks says that the material will be cheaper than Monsanto Clear Pass.