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Truck Transmission Help

Truck Transmission Help

How can I best search to find a truck with the right Gearbox?

You would think it would be straightforward – you either have a manual or an automatic gearbox like in a car. In many ways this is true. Unfortunately the truck manufacturers are so proud of their gearboxes that they give them brand names. So when a Volvo Trucks dealer talks about a truck being fitted with an’I-Shift’ gearbox is this manual or automatic? The simple answer is a bit of both.

Manual Truck Gearbox

A manual gearbox is easy to explain, the driver uses a clutch and changes gear – there’s usually more of them in a truck than in a car – up to 16 in some. Think of the gears more like a racing pedal bike than a car and they are easier to understand. A bike has eight gears at the rear and then three on the front giving three lots of eight gears. The same principal operates for trucks. Larger trucks will have six forward gears and then three ‘splitters’ which will give three extra ratios for each gear. An alternative to the ‘splitter’ type are ‘range change’ gearboxes, where, instead of splitting each gear, the driver will use all four, then flip a button whilst moving from fourth back into what was first, but becomes fifth!

Smaller trucks are more straightforward, however, some with none or just six gears.

Automated Truck Gearbox

Mercedes Powershift gearbox

These are manual gearboxes that have some clever computer-controlled gadgets that control the physical changing of the gears, leaving the driver to focus elsewhere and, in most cases improving fuel efficiency, as driving a manual truck with 16 gears means that it is easy to be in the wrong gear some of the time. Unlike with an ‘automatic’ gearbox that uses a hydraulic system and a torque converter there is a loss of power the automated gearbox gets the efficiency benefits of a manual gearbox with the driver aids of an automatic. This is the type of gearbox they use in formula one. Look out for the truck makers brands to spot an automated gearbox such as Renault Trucks Optidriver, Mercedes-Benz Powershift, Scania’s two- or three- pedal Opricruise, Iveco’s Eurotronic and DAF’s AS-Tronic.

Automatic Truck Gearbox

As far as trucks are concerned, fully automatic gearboxes are kept for very local multidrop work such as refuse vehicles, (and buses). The transmission of power to the wheels is more gradual and even than a manual or automated gearbox can be.  Most of these types of gearbox are made by Allison in the USA.

Gearboxes in Used Trucks

Where's the gearstick?

The number of trucks sold as new with an automated gearbox as standard is on the increase and it is likely that over the next few years, a manual gearbox will become a cost option on all new trucks. The driver and operator benefits are so great in terms of fuel returns and the ability of the truck to do more thinking. For example, Volvo and Mercedes-Benz have systems that know what is ahead on the road and will select the correct gear before it needs it – for example when there is a hill coming up.

So, if a truck is listed as automatic it is more likely than not and automated gearbox – unless it is a genuine rarity or a dustcart with an Allison automatic gearbox.