No engine breaking.

[muskrat]

G'day Fellas.
I always thought (probably wrong as never investigated it) that diesel exhaust brakes were the effect of limiting the exhaust valve (sort of like a reversed decomp). Now I've asked the question it's off to Dr Google!
Cheers

[Triton Thrasher]

G'day Trevor.
I've often wondered why petrol engines don't have exhaust brakes like diesel trucks?
Cheers

There’s more of a worthwhile benefit for heavy goods vehicles going down long hills. 

[Triton Thrasher]

G'day Fellas.
I always thought (probably wrong as never investigated it) that diesel exhaust brakes were the effect of limiting the exhaust valve (sort of like a reversed decomp). Now I've asked the question it's off to Dr Google!
Cheers

The ones I worked with were a fairly simple air powered gate valve across the exhaust pipe, close to the manifold.

Pressing the heel button closed that valve and shut off the fuel.

[muskrat]

G'day TT.
So such a system might work with a FI petrol motor if the spark was also cut. The greenies might complain.
Cheers

[Black Sheep]

I would suggest that the throttle is not closing completely. Fit a stronger return spring and see what happens. Also if your bike is manual advance, retard the ignition when you close the throttle and see if that makes a difference.

[RDfella]

Not a device I'd recommend. For a start, most trucks these days are artic, so braking the tractor rears only would acerbate the risk of jackknife. Then, looking at the effects on the engine - again, virtually all are turbo diesel. Restricting the exhaust would be after the turbine housing, meaning pressure would build up in there whereas normally it's a through-flow of hot gas. Secondly, with pressure build up in the cylinders, eventually some will release when the inlet opens, meaning gases going back through the intercooler into the compressor housing. Frankly I'd rather replace a few sets of pads and shoes rather than do more frequent engine rebuilds. Leave the engine for pulling and the brakes for slowing.

[Triton Thrasher]

Not a device I'd recommend. For a start, most trucks these days are artic, so braking the tractor rears only would acerbate the risk of jackknife.

Sounds like you’ve never driven a vehicle equipped with a retarder of any type. Or an artic.

 

Then, looking at the effects on the engine - again, virtually all are turbo diesel. Restricting the exhaust would be after the turbine housing, meaning pressure would build up in there whereas normally it's a through-flow of hot gas. Secondly, with pressure build up in the cylinders, eventually some will release when the inlet opens, meaning gases going back through the intercooler into the compressor housing.

It’s good that you can think stuff up like that. We do need imaginative engineers.  Exhaust brakes were in near-universal use in new (turbocharged) artics when I started driving and working on goods vehicles in 1979.  Nowadays I believe I can hear them chirping in buses too. 

They haven’t destroyed all the engines yet!

 

Frankly I'd rather replace a few sets of pads and shoes rather than do more frequent engine rebuilds. Leave the engine for pulling and the brakes for slowing.

That is slightly shocking.  Fortunately, no driver would ever pay it any attention. 

I bet I’m not the only guy here who is familiar with the tragic results of heavy vehicle brakes being relied on to control speed down long hills.

[RDfella]

TT- I held an HGV for 53 years and driven many an artic. Judging by your comments. no sure I'd want to be on the road close to you though.

[Triton Thrasher]

Well I’ve still got the licence nya nya!

[Greybeard]

Play nice, children

[berger]

i did not go to the pub, my dad was instructed to drive wagons in WW2 using the gearbox to slow down. in the early 70's himself and a scrap dealer were having a chin wag about this because my dad used to double de clutch into 1st gear in his moggy thou. the scrap man said " cyril it's easier and less cost to change brake shoes than gearbox's. i will never forget that statement even though i heavily engine brake the betsy beast, it sounds rate good 

[Jules]

A man after my own heart, use the gearbox to slow down for hills and bends, save the brakes for when you need to stop! We live on a (small!) mountain and the road down to the shops has traffic lights around the bend at the bottom. Many a truck (and even cars!) have had issues with burnt out brakes when (trying) to stop at the bottom because when you follow them down they are sitting on their brakes continuously.....

[Greybeard]

I was taught to use the gears as part of the braking process. Back then, my cars brakes needed all the help they could get. Changing down also leaves you in a suitable gear ratio for the next section of road. As I got older and my driving style calmed down, I still changed down but no longer screaming the engine;  just putting the gears in a suitable ratio for my speed.

I currently drive an automatic hybrid Honda Jazz that has the normal D and R but also B on the gear lever. The B position uses the engine/generator on over-run to provide additional drive battery charge that acts like engine braking.

[Black Sheep]

There ae still plenty of signs around stating "Steep Hill Select Low Gear".

[bikerboy]

A man after my own heart, use the gearbox to slow down for hills and bends, save the brakes for when you need to stop

The main reason that people were encouraged to use the brakes and not the gears was to ensure that the brake lights came on warning people behind you that you were slowing or stopping, obviously using the gears does not warn following vehicles.

On most of the modern day artics brake lights come on when the full retarder is used and the hazards (4 ways for our american readers) also come on when you brake heavily.

Not saying I agree with the theory but thats why braking is encouraged.