Driving economically

[TripleS]

our LGV's have a retarder on the gearbox (automatics) which is actuated by the driver coming off the throttle, it also switches the brake lights

Is a retarder the same as the RBS then?

With your retarder does it mean you find yourself needing to 'feather the throttle pedal' more ? It sounds as if it could be a bit tricky to me, but I expect it is something you become accustomed to.

Best wishes all,
Dave.

[OILY PAWS]

our LGV's have a retarder on the gearbox (automatics) which is actuated by the driver coming off the throttle, it also switches the brake lights

Is a retarder the same as the RBS then?

With your retarder does it mean you find yourself needing to 'feather the throttle pedal' more ? It sounds as if it could be a bit tricky to me, but I expect it is something you become accustomed to.

Best wishes all,
Dave.

having been involved in a RTC while enroute to an incident, which I reckon was caused by the retarder, where the driver could not regain control of the vehicle, IMO this device shouldn't be fitted to vehicles which need to be driven in the manner we drive ours, I can see how they would be an advantage in a "NORMAL" LGV though

[ScoobyChris]

I've heard of regenerative braking systems on large heavy vehicles, but I didn't know it was on any cars.

BMW have "Brake Energy Regeneration" on a lot of their new cars which has helped them to get better fuel consumption figures. Not sure on the technical details, but the marketing speak is at http://www.bmw.co.uk/bmwuk/efficient_dy ... generation

Chris

[TripleS]

I've heard of regenerative braking systems on large heavy vehicles, but I didn't know it was on any cars.

BMW have "Brake Energy Regeneration" on a lot of their new cars which has helped them to get better fuel consumption figures. Not sure on the technical details, but the marketing speak is at http://www.bmw.co.uk/bmwuk/efficient_dy ... generation

Chris

Thanks, Chris. That's another new one on me but I'll have a look.

Best wishes all,
Dave.

[Roger]

Brakes for slow and gears for go makes tremendous sense in hybrids (Prious, Civic IMA, Lexus GS450) thanks to regenerative braking, provided the driver anticipates sufficiently well that the brake can be applied sufficiently lightly that friction dissipation is not called into significant play.

I've heard of regenerative braking systems on large heavy vehicles, but I didn't know it was on any cars.

How do you activate the regenerative braking system only, without bringing the normal braking system into play? Is there a separate control (i.e. other than the brake pedal) to operate the RBS ?

Best wishes all,
Dave.

It's automatic. Press the brake gently - or go downhill with the foot off - and you get regeneration. Press it harder, or do it for too long (when the battery is maxed out) and the pads come seamlessly in to play. See http://www.honda.co.uk/IMA/ for more detail.

I tet-drove one about 18 months ago and was VERY impressed. Not as fast as an Accord of course, but really spunky silent smooth acceleration up to 70 and very economical.

[waremark]

BMW have "Brake Energy Regeneration" on a lot of their new cars which has helped them to get better fuel consumption figures.

I think that all the BMW system does is to disconnect the alternator for most of the time, and only connect it under braking. This allows the alternator to get enough power to keep the battery charged while the engine is using no fuel, and never having to use valuable energy to drive the alternator. I think the alternator can be reconnected under power if necessary to keep the battery charged.

No doubt this system makes a worthwhile but modest contribution to economy. The new M3 has it but will be lucky to achieve as much as 20 mpg.

However BMW diesel engines in particular are in the forefront for their low emissions levels in relation to the power outputs. For example the X5 3.0D comes in under 220 g/km of CO2 output (the Band G threshold) whereas no Range Rover or Mercedes ML models do so, in spite of generally less good performance. Similarly the 118D is one of the best performing cars in Band B which is taxed at only £35 pa.

[Renny]

having been involved in a RTC while enroute to an incident, which I reckon was caused by the retarder, where the driver could not regain control of the vehicle, IMO this device shouldn't be fitted to vehicles which need to be driven in the manner we drive ours, I can see how they would be an advantage in a "NORMAL" LGV though

I think Fife has had a couple of those type of incidents. I've been promised a drive of one of the appliances by our Fleet Engineer as he told me the retarder is "different". I think I'd prefer a switchable system where the operation could be either on closed throttle, or light application of brake pedal (as per most trucks), or by seperate control. I suppose one problem is that different drivers would select different features and that could cause problems on a shout.

[OILY PAWS]

having been involved in a RTC while enroute to an incident, which I reckon was caused by the retarder, where the driver could not regain control of the vehicle, IMO this device shouldn't be fitted to vehicles which need to be driven in the manner we drive ours, I can see how they would be an advantage in a "NORMAL" LGV though

I think Fife has had a couple of those type of incidents. I've been promised a drive of one of the appliances by our Fleet Engineer as he told me the retarder is "different". I think I'd prefer a switchable system where the operation could be either on closed throttle, or light application of brake pedal (as per most trucks), or by seperate control. I suppose one problem is that different drivers would select different features and that could cause problems on a shout.

As explained to me, the retarder systems are two stage in operation, supposedly a "soft- start" when you lift the foot and when off throttle completely brake lights on a greater braking effect occurs, one of the reasons being bandied about for ths cause of the RTC was the settings, of the retarder, i.e they were set for an appliance a lot heavier, which has a larger proportion of it's weight over the rear axle. IMO they shoudn't be fitted to Fire Appliances, as they remove an element of control, they must be brilliant on an LGV having to slow down say a steep incline, like the M90 down to Bridge of Earn.........

[Mr Cholmondeley-Warner]

Where does the energy from this "retarder" go? About the only thing you can do with excess energy in an internal combustion engine is drive a generator to charge the battery, and that isn't going to have much retardative effect on an HGV...

(yes I know some of it is used by the heater).