Adding a Layshaft to the Gearbox

With the introduction of the New Generation trucks, Scania has unveiled an improved driveline for its models, adding a layshaft to the gearbox. Getting out on the road with these trucks gives Diesel Workshop a clear idea just how many small improvements have been made to get the whole truck into the next generation.

Adding a Layshaft to the Gearbox

The most obvious example from the driver’s seat is the way the Opticruise AMT changes gear. We are used to AMTs which make split second changes, well, Scania’s just got quicker again.

The new Opticruise now includes a layshaft, a second shaft running parallel to the main shaft, to and from which drive can be transferred, this improves up shifting. The new system can synchronise the speed of the main shaft and the gear, almost instantaneously, making for very swift changes. On a slight up grade with 60 tonnes on board the power is hardly interrupted on an up shift.

While the top-end V8 engines retain their current power and torque ratings, up to 730 hp (537 kW) at 1900 rpm and 3500 Nm (2580 ft lb) of torque at 1000-1300 rpm. There have been improvements, with an all new engine management system on all engines and improved cooling of the engine under the new cab.

Meanwhile the new 13 litre engines have gone over to using only SCR to control emissions at Euro 6. There is no EGR system involved in the engine design, reducing cooling needs and freeing up the  running of the engine. The top power 13 is now the 500 hp (373k kW), with torque coming out at 2550 Nm (1881 ft lb).

Adding a Layshaft to the Gearbox

Out on road the new SCR engine shows its mettle. Traveling around the 40 minute course at 60 tonnes, of course, the V8 just ate it up, hauling up the grades with little effort and maintaining momentum with going over 1500 rpm at any point. It seems to settle around the 1200 mark very easily.

Jumping into a similar combination at similar weights, but with the 500 hp SCR engine under the cab, saw little change. The engine feels willing to go hard at all times, with minimal effort. Average speed may have been a little slower, when compared to the big V8, but not that much. Conventional wisdom has it, the engine needed at this mass needs to be 550 hp plus. Driving this 500 suggests an astute operator might try this engine and get the payload and fuel savings on offer.

Fuel savings is a big ticket item in Europe right now, and should be more important here. Scania are talking about a five per cent reduction in fuel use across the range. This consists of three per cent from the driveline and a further two per cent from the improved aerodynamics of the new cab.

 

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Author: Tim Giles

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