Driving test in an electric car

I just about remember those. How quaint. ;-)

Tim

Diesel-hydraulic competed with diesel-electric in the '50s and '60s. BR simply decided to standardise on diesel-electric and withdrew the diesel-hydraulics. Prior to that, they were successfully hauling passenger express trains. Germany continued to use diesel-hydraulics for many years.

Apart from certain expensive ones, they don't have an auto or a manual transmission. They have a fixed gearing from motor to final differential.

Can't really see the point in anything else. They certainly haven't reduced the number of cars you see where the brake lights are on when stopped in traffic.

But your confusing issues now. My point was was that it’s courteous to use your handbrake when stopped, especially at night in the rain, rather than use auto-hold which keeps the brake lights on.

The electrification or otherwise of your handbrake makes no difference. Autohold doesn’t, generally (as far as I know), use the handbrake mechanism.

Tim

only if it has been on for ages, and the ABS unit starts to overheat, the it applies the electric handbrake instead.

I'm sure I recall reading about a diesel-hydraulic that "changed gear" by having several torque converters and pumping the fluid in and out of them.

Not very reliable AIUI... I can't find a reference.

Andy

The more logical way would be to have them in series, with lockup clutches?

For a road hydraulic transmission, the pump can have a variable swash plate. Changing its angle changes the pump delivery volume, increasing fluid flow and so adjusting the drive motor speed. Setting the swash plate flat delivers nothing. There is therefore no need for gears, clutches or torque converters.

Some diesel-hydraulic rail vehicles used a similar system, but could vary their delivery smoothly or in steps - in step mode they replicated the gear change steps of diesel-mechanicals, so the two could work together in multiple, with matching characteristics.

It seems that locos used multiple torque converters, driving multiple fixed gear sets, to give 3 or 4 ratios.

I have two cars, each with the VW Audi Group 7-speed DSG box. Completely brilliant bit of kit.

There was the Citreon DS Palace with the hydraulically operated gear-box and clutch

Dave