Thread: A myth busted! For me anyway

neutral

Originally Posted by paulthepilot_5

"angel gear" Please Explain!

Also called Mexican overdrive. Coasting down steep grades in neutral. Much practised by truckies of my generation. Driving with the angels. A compensatory measure for lack of horsepower in the days when linehaul prime movers were lucky to have 250 hp. Up the hill at 5kph and float down at 140. And also a life & engine saving measure when said prime movers had minimal brakes. Also known as "floating". A practised floater on the right road could float for up to 22 kilometres on sections of the old New England Highway. Oft-times one would have to throw her out and float when the braking systems of the time gave in, and hang on and hope, or, if travelling slow enough, jump out and leave her. Try losing all brakes downhill on the Toowoomba Toll Bar and hanging on until well past Withcott. See what colour your face and underpants are after that. Happened to me with a Commer TS3 "Knocker" with a bogie trailer of wool ( illegal loading then).

Ok, I had heard the term used by someone who used to drive centurion tanks! It was called out to the rest of the crew if they were going down hill and the thing didn't go into gear, In other words, Hold The F**k on!

kerist, I wonder how tracks hold up at those speeds.
schmokin

Yep, It would be a bit of a worry, if you were driving down hill in front of a centurion, an 80tonne block of steel on tracks is not going to stop too stop in a hurry

I dont know about input shaft bearings life span but it is more than likly that coasting in neutral at those sort of speeds was called angel gear as that was where you would end up, with the angels (and not charlies angels) or in other words, would shorten the drivers life expectancy.

I know for a fact that a SIIa shorty can coast from halfway back from tolmie into mansfield as I have been in one that has done it and I can tell you it was not much fun as he didnt touch the brakes the whole way down.

my 2 c on this...

dont idle your engine on startup let it get oil pressure, count to 10 then drive off... shut downs can vary.....

If youve been working the box off of it it will be hot even NA engines will benefit from a 2-3 minute cool down to "normalise" the engines themal loading. the reason is simple, if you shut down a freshly hard worked cast iron engine it has a lot of latent heat in parts of it (piston heads, the sides of the block, con rods manifolds) that dont have access to the "wet" cooling system. When you shut down you stop the coolant circulating and stop the airflow in the engine bay, as the parts of the block pass the stored heat back into the cooling system its possable to have the engine overheat while its shutdown.. The same holds true for an alloy engine but the times are shorter as aluminium is a much better conductor of heat. Turbo engines follow the same rule but also have the turbo to worry about for reasons that IMHO have been perfectly delt with already.

There are a few circumstances when you DO NOT shut down your engine for a prolonged holt. when its COLD... If your above the alpine line and its cold enough (below the minimum intifreze temp of your coolant) you dont shut down the engine for a prolonged halt. If the cooling system freezes you have to defrost it somehow before starting up or you will frell the engine.. In some cases if the battery is not preforming due to the cold and the block and air is cold enough a diesel wont create enough heat from compression to start itself which is why in places like canada cars are fitted with electric engine warmers.

Originally Posted by Blknight.aus

my 2 c on this...

dont idle your engine on startup let it get oil pressure, count to 10 then drive off... shut downs can vary.....

If youve been working the box off of it it will be hot even NA engines will benefit from a 2-3 minute cool down to "normalise" the engines themal loading. the reason is simple, if you shut down a freshly hard worked cast iron engine it has a lot of latent heat in parts of it (piston heads, the sides of the block, con rods manifolds) that dont have access to the "wet" cooling system. When you shut down you stop the coolant circulating and stop the airflow in the engine bay, as the parts of the block pass the stored heat back into the cooling system its possable to have the engine overheat while its shutdown.. The same holds true for an alloy engine but the times are shorter as aluminium is a much better conductor of heat. Turbo engines follow the same rule but also have the turbo to worry about for reasons that IMHO have been perfectly delt with already.

There are a few circumstances when you DO NOT shut down your engine for a prolonged holt. when its COLD... If your above the alpine line and its cold enough (below the minimum intifreze temp of your coolant) you dont shut down the engine for a prolonged halt. If the cooling system freezes you have to defrost it somehow before starting up or you will frell the engine.. In some cases if the battery is not preforming due to the cold and the block and air is cold enough a diesel wont create enough heat from compression to start itself which is why in places like canada cars are fitted with electric engine warmers.

I have seen while working on Mt Buller, busses and some 4wd's have snow shutters on their radiator intakes and aircleaners, like your typical Jap carbi aircleaner in the 80's, they would pick up air from around the exaust so the intake air was heated shortly after starting.

It makes sense to me now why they did it as it was one of those things that I thought was unnessesary and something that was cheap to add and could sway a sale to companies buying the vehicals for snow areas.

Interesting.