With so many models of wheel play detectors on the market to choose from, Boston has summarised the key questions to ask and the main features to look for before purchasing.
Pneumatic or hydraulic?
The first thing Boston says you need to decide on is whether to choose a pneumatic or a hydraulic model.
Both types perform equally well with standard vehicles, but when vehicles are slightly heavier than the norm, or loaded when presented for an MOT test, this is where having a high-quality unit pays.
Hydraulics will always win over pneumatic and in our opinion, with vehicles becoming larger and heavier, it would be prudent to choose a hydraulic unit.
UK force specifications
UK specifications state that all play detectors, hydraulic or pneumatic, must apply at least 8kN of force on the moving plate in order to sufficiently move the road wheel of any vehicle presented for Class VL and Class VII testing (6kN for Class IV).
However, not all models achieve this; some have been approved on their merits by demonstrating that the wheel is moved ‘enough’ to show play in key components meaning that play will be more difficult to detect on larger vehicles.
As play detectors are usually supplied as an integral part of a four post lift, be cautious when selecting a new vehicle lift and always ask whether the play detectors meet the actual UK force specification.
UK plate movement specifications
UK specifications also state that play detectors should have “a lateral movement of at least 40mm in each direction from the central position, and a pivotal movement through a minimum arc of 8 degrees in each direction from the straight-ahead position”.
As before, some equipment has been approved on its merits by demonstrating adequate movement of the wheel.
However, in some circumstances, and where vehicles are larger, it may prove difficult to carry out a proper test on models that have less travel or smaller plates sizes than others.
Equipment operation speed?
Play detectors should not operate fast and violently, this is simply unnecessary as any wear or play is easily seen through a steady and controlled movement of the plate.
There have been instances where lift mounted play detectors operating too violently have affected the fixing bolts and even the integrity of the welded sections on some four post lifts, to the extent that they have been deemed dangerous or even condemned by insurance assessors!
The point here is that fast and furious is not necessary and can only serve to add extra stress to the vehicle lift.
Single or dual plate system?
The specification calls for two types of movement, lateral and rotation; units with two plates usually restrict one type of movement to each plate separately.
This is logical and effective, but the same movements can also be achieved using a single plate with carefully thought through hydraulic cylinder positions and geometry.
There are no major benefits to either type, but when it comes to vehicle inspection pits it is somewhat easier for the civil work to select a unit with a single plate.
As vehicle lift play detectors are often built into the lift and share the same hydraulics, you are bound in this case by the type supplied by the manufacturer.
Single-phase or three-phase?
The most common reasons for choosing a single-phase unit is to save on the cost of running an additional three-phase power supply to a specific area of the building, or because three-phase isn’t available in the premises (common with rural garages).
Lift integrated play detectors are governed by the power supplied to the lift, which is usually three-phase.
In terms of performance, both types will function equally well meaning that other than cost, there is no real benefit in choosing one over the other.
Handheld control torch
The handheld control torch is the most used part of this product. Some controls use low cost plastic housings which are not impact resistant, making them prone to damage.
Controls need to be durable and well made, and because the play detector is such a key item in the test lane, it must be operational at all times. Always consider the quality of the control unit and check the price and availability of spares or replacement components.
Wireless control torch option?
A good quality wireless torch provides a much better user experience than hard-wired types.
Due to the nature of the product, the torch is repeatedly lifted high and low, causing the cable to be twisted, tugged and stretched on virtually every MOT test.
If a wireless option is available, then it will certainly be worth the extra cost.
When considering wireless options, always check the operational usage time when fully charged; it’s common for testers to also use the torch to carry out inspection of other parts of the vehicle, so you want the control to have a good battery capacity.
You should also ask about the cost of replacement parts in case a repair is needed – from some suppliers this can be very high.
As most play detectors are manufactured in Europe (or further abroad), this can result in long lead times on any necessary replacement parts; it’s important to check before you purchase that spare parts are available immediately if required.
Handsets and remote controls are often dropped or driven over in the workplace and you need to be confident that you can get a replacement the next day.
Play detectors are used on every test, day-in and day-out, and as such they are prone to wear and tear especially as they contain pumps and hydraulic rams.
The warranty period offered by many suppliers is mostly limited to just 12 months but some manufacturers offer longer terms.
Be sure to ask the question as many of these key components are expensive to replace.
For more information call 01708 525585 and ask to speak to Ross or Richard, or click “more details” below.