Automatic transmission is possibly the single most significant vehicle technology for easy towing, says Ian Shaw
NOTHING DIVIDES OPINION among drivers like manual or automatic transmission. But let’s leave aside any prejudices to look at why caravanners love the auto ’box. We’ll also leave aside its most obvious trait – merely being labour-saving.
First, the friction clutch of a manual gearbox is a necessary evil, and a crude one at that. It must be manipulated simply to move off, let alone select ratios.
Automatics were initially entirely about labour-saving. Early types were actually automated-manual devices, the like of which (with a raft of electronics) now reside in today’s 44-tonne artics.
Then the torque-converter (fluid flywheel) ousted the single friction clutch, meaning moving off was now purely an accelerator pedal affair.
That’s the automatic’s first advantage for towing.
The car’s handbrake might hold on a 25% incline, but few will manage a twin-axle tourer, too, whose over-run brakes are inert here. In a manual, that required heel-and-toe dexterity between brake and gas, as the clutch bit, or abuse of said friction plate for the duration of a red light.
Once you are on the move, the torque-converter passes drive from the engine to the transmission continually, with gear selections made by several internal clutches – one per ratio – and their actions barely felt, finely controlled and immune from abuse. A more elegant engineering solution; always in the right gear, the engine cannot be made to labour or over-rev.
More control
Those who dislike automatics cite lack of driver control or involvement, but today, not only can drivers decide on the characteristics of the auto ’box, they can also manually select from six to 10 separate ratios, at the flick of a paddle. So how does that help caravanners?
It’s simple – you never pass through neutral, a mis-shift is impossible and the torque flow is uninterrupted. Labour-saving, but a better solution.
Continuously variable transmission (CVT) – most commonly used in twist-n-go scooters – takes this a
