Wheel Slippage, Coupler Failure, Slack Management and Bad Winter Drivers

Posted by PITHOCRATES - January 8th, 2014

Technology 101

Starting a Train to Move is like Starting a Car to Move on Snow and Ice

Starting and stopping a train takes great skill.  Because one of the greatest advantages of rail transport is also one of its greatest weakness.  Steel wheels and steel rails.  With very little friction between the two.  Allowing trains to travel very efficiently.  Rolling effortless over great distances.  Once they get moving, that is.  Which is where that skill comes in.

Starting a train to move is like starting a car to move on snow and ice.  If you stomp the accelerator the wheels will just spin on the snow and ice.  Just as steel wheels on steel rails will.  Because of the low amount of friction between the two.  The throttle on a North American locomotive has 8 ‘run’ positions.  And one ‘idle’ position.   The engineer starts the train moving by moving the throttle to position one.  As the train begins picking up speed the engineer advances the throttle through all the positions until reaching run eight.

As the engineer moves the throttle he (we will use the pronoun ‘he’ for simplicity in lieu of ‘he or she’) watches the amp meter and wheel slip indicator.  Which is why he advances the throttle through each position.  To slowly start the train moving.  If he ‘stomped the accelerator’ the wheels would slip and spin freely on the steel rail.  Damaging both wheels and rail.  Without moving the train.  In addition to preventing wheel slippage he is also trying to prevent one other thing.  Coupler failure.

Getting a Train Moving is Difficult but Keeping it Safely on the Track can be Harder

Driving a train is a study in slack management.  Each coupler on a train has slack in it.  They are not permanently affixed to the railcar or engine.  They can move forward and backward a little bit.  With a shock absorbing device that deals with the compression and tension forces between cars.  This slack exists at each coupler.  The longer the train the more couplers and the more slack.  When a train starts moving it takes very little effort to pick up the slack in a coupler.  But it takes a lot more effort to get the car moving once you do pick up the slack.  And if you apply that force too quickly you can snap the coupler right off of the car.

An engineer picks up this slack by moving slowly while in run one.  And he moves slowly by having the brakes partially set.  That is, he moves the throttle to run one and slowly releases some air in the train line.  As he does the brakes release.  A little bit.  Just enough to allow the train to move at a crawl.  Slowly picking up the slack without breaking a coupler.  Once he picks up all the slack he releases the brakes completely.   And slowly picks up speed.  Able to pull great weights of freight trailing behind as there is so little friction between steel wheels and steel rail.

Of course, that is also a problem.  For curves.  Where the engineer has to slow the train down so the centrifugal force doesn’t pull the train off the tracks.  Or on gradients.  Where the engineer has to slow the train on downhill portions to prevent a runaway.  Or add sand to the track on uphill runs (through automatic sand feeders in front of the drive wheels).  To prevent wheel slippage by adding friction between the wheel and track.  Getting a train moving is difficult.  But keeping it safely on the track can be harder.  Which requires the ability to slow a train in time for curves and downhill gradients.  Which takes time.  And a mile or so of track.

When it comes to Driving a Car in the Winter you have to approach it like Driving a Train

Driving a train is like driving a car on snow and ice.  There’s a lot of wheel slippage.  It’s difficult to slow down.  And you really have to slow down for curves.  For if you turn the steering wheel at speed your front wheels will just slide across the snow and ice and the car will keep going straight.  If you stomp on the brake pedal and lock the wheels your wheels will just slide across the snow and ice in the general direction you were traveling in.  Today, modern cars have systems to help people drive on snow and ice.  Like anti-lock brake systems.  And traction control systems.

An anti-lock brake system prevents the wheels from locking up during braking.  The system monitors wheel rotation.  If it senses a wheel that is no longer rotating it will begin pulsating the brakes.  Applying and releasing the brakes some 15 times a second.  So the wheel keeps rotating, giving the driver control.  A traction control system also monitors wheel rotation.  If it senses a wheel rotating faster than another (because it’s spinning in ice and snow) it will slow that wheel and/or apply more power to the non-slipping wheel.  Giving today’s drivers more control of their cars in the ice and snow.

Of course none of these systems will help if the driver is irresponsible behind the wheel.  And lazy.  If you don’t shovel your driveway after it snows.  Or if you do but push that snow into the street in your driveway approach.  For a car needs to have the rubber in contact with the pavement for traction.  If not you get wheel slippage.  And we all probably have a neighbor who thinks the best thing to do when this happens is to step down on the accelerator.  To spin those wheels faster.  And does.  Digging a hole in the snow.  And then begins swearing because the stupid car got stuck in the snow.

When it comes to driving a car in the winter you have to approach it like driving a train.  You need to start slowly and monitor your wheel slippage.  Sometimes it’s best to just let the engine idle in gear to slowly get the car moving.  Then once the car is moving on top of the snow and ice you can slowly increase the speed.  But never so much to cause wheel slippage which will just dig a hole in the snow and ice that you may not be able to drive out of.  And you have to start slowing down long before you have to stop.  Always being careful not to lock your wheels.  Simple stuff.  Something every driver can do.  For these are things every engineer does.  And driving a locomotive is a lot more difficult than driving a car.

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Waterwheel, Rotational Motion, Reciprocal Motion, Steam Engine, Internal Combustion Engine and Hydraulic Brakes

Posted by PITHOCRATES - December 5th, 2012

Technology 101

To Keep People on Trains they Undercharge Passengers and make up the Difference with Government Subsidies

We built some of our first factories on or near a river.  Where we could use that river’s current to turn a waterwheel.  To provide a rotational motion that could do work for us.  We transmitted that rotational motion via a main drive shaft through a factory where it could drive machinery via belts and pulleys.  Once we developed the steam engine to provide that rotational motion we could move our factories anywhere.  Not just on or near a river.  Giving us greater freedom.  And permitting greater economic growth.  As we put those steam engines onto rails.  That transported freight and people all across the country.

Trains are nice.  But expensive.  To go anywhere on a train you need train tracks going there.  But train tracks are incredibly expensive to lay.  And maintain.  If you ever stared at a set of train tracks you probably noticed something.  There aren’t a lot of trains going by on them.  When a train stops you when you’re running late or bringing home dinner it may feel like trains are always stopping you.  But if you parked at those same tracks for a few hours you wouldn’t see a lot of trains.  Because even the most polished rails (the more train traffic the more polished the rails) are unused more than they are used.

This is why trains are very expensive.  Tracks cost a lot of money to lay and maintain.  Costs that a railroad has to recoup from trains using those rails.  And when you don’t have a lot of trains on those rails you have to charge a lot for the trains that do travel on them.  A mile-long train pulling heavy freight can pay a lot of revenue.  And make a railroad profitable.  But passenger trains are not a mile long.  And carry few people.  Which means to make money on a passenger train you’d have to charge more for a ticket than people would pay.  To keep people on trains, then, they have to undercharge passengers.  And make up the difference with government subsidies.

A Crank Shaft and Combustion Timing takes Reciprocal Motion of Pistons and Converts it into Rotational Motion

This is why people drive places instead of taking the train.  It’s far less expensive to take the car.  And there are roads everywhere.  Built and maintained by gas taxes, licenses and fees.  And if you’ve ever driven on a road you probably noticed that there are a lot of cars, motorcycles, trucks and buses around you.  With so many vehicles on the roads they each can pay a small amount to build and maintain them.  Which is something the railroads can’t do.  Only trains can travel on train tracks.  But cars, motorcycles, trucks and buses can all travel on roads.  This is why driving a car is such a bargain.  Economies of scale.

To operate a train requires a massive infrastructure.  Dispatchers control the movement of every train.  Tracks are broken down into blocks.  The dispatchers allow only one train in a block at a time.  They do this for a couple of reasons.  Trains don’t have steering wheels.  And can take up to a mile to stop.  So to operate trains safely requires keeping them as far apart from each other as possible.  Traveling on roads is a different story.  There are no dispatchers separating traffic.  Cars, motorcycles, trucks and buses travel very close together.  Starting and stopping often.  Traveling up to high speeds between traffic lights.  With motorcycles and cars weaving in and out among trucks and buses.  Avoiding traffic and accidents by speeding up and slowing down.  And steering.

Driving a car today is something just about anyone 16 and older can do.  Thanks to the remarkable technology that makes a car.  Starting with the internal combustion engine.  The source of power that makes everything possible.  Just like those early waterwheels the source of that power is rotational motion.  But instead of a river providing the energy an internal combustion engine combusts gasoline to push pistons.  A crank shaft and combustion timing takes that reciprocal motion of the pistons and converts it into rotational motion.  Spinning a drive shaft that provides power to drive the car.  As well as power all of its accessories.

The Friction of Brake Shoe or Pad on Steel slows the Car converting Kinetic Energy into Heat

The first cars required a lot of man-power.  It took great strength to rotate the hand-crank to start the engine.  Sometimes the engine would spit and cough.  And kick back.  Breaking the occasional wrist.  Once started it took some leg-power to depress the clutch to shift gears.  It took a little upper body strength to turn the steering wheel.  And some additional leg-power to apply the brakes to stop the car.  In time we replaced the hand-crank with the electric starter.  We replaced the clutch and gearbox with the automatic transmission.  We added power steering and power breaks to further reduce the amount of man-power needed to drive a car.  Today a young lady in high heels and a miniskirt can drive a car as easily and as expertly as the first pioneers who risked bodily harm to drive our first cars.

The internal combustion engine can spin a crankshaft very fast and accelerate a car to great speeds.  Which is good for darting in and out of traffic.  But traffic occasional has to stop.  Which is easier said than done.  For a heavy car moving at speed has a lot of kinetic energy.  You can’t destroy energy.  You can only convert it.  And in the case of slowing down a car you have to convert that kinetic energy into heat.  When you press the brake pedal you force hydraulic fluid from a master cylinder to small cylinders at each wheel.  As fluids cannot compress when you apply a force to the fluid that force is transmitted to something than can move.  In the case of stopping a car it is either a brake shoe that presses against the inside of the car’s wheels.  Or a caliper that clamps down on a disc.  The friction of brake shoe or pad on steel slows the car.  Converting that kinetic energy into heat.  In some cases of excessive braking (on a train or a plane) the heat can be so excessive that the wheels or discs glow red.

So as the internal combustion engine and the brakes play their little games of speeding up and slowing down a car the rotational power of the crankshaft drives other accessories.  Such as power steering.  Where a belt and pulley transfers that rotational power to a power steering pump.  The pump pushes fluid to the steering gear to assist in turns.  Another belt and pulley connects an alternator to the crankshaft to produce electricity to provide power for the car’s electrical systems.  And to charge the battery so it can spin the automatic starter.  Another belt and pulley connects another compressor to the crankshaft.  This one for air conditioning.  That allows us to alight from our cars shower-fresh on the hottest and most humid days of the year.  And, finally, antifreeze removes the heat of combustion from the internal combustion engine and transfers it to a heating core inside the passenger compartment.  Allowing a warm and comfortable drive home during the coldest of days.  As well as keeping our windows free of snow and ice so we can see to drive safely on our way home.  Through bumper to bumper traffic.  Something we do day after day with the ease of doing the laundry.  Thanks to the remarkable technology that we take for granted that makes a car.

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Trade, Steam Power, Reciprocating Steam Engine, Railroading, Janney Coupler and Westinghouse Air Brake

Posted by PITHOCRATES - January 25th, 2012

Technology 101

Early Cities emerged on Rivers and Coastal Water Regions because that’s where the Trade Was

The key to wealth and a higher standard of living has been and remains trade.  The division of labor has created a complex and rich economy.  So that today we can have many things in our lives.  Things that we don’t understand how they work.  And could never make ourselves.  But because of a job skill we can trade our talent for a paycheck.  And then trade that money for all those wonderful things in our economy.

Getting to market to trade for those things, though, hasn’t always been easy.  Traders helped here.  By first using animals to carry large amounts of goods.  Such as on the Silk Road from China.  And as the Romans moved on their extensive road network.  But you could carry more goods by water.  Rivers and coastal waterways providing routes for heavy transport carriers.  Using oar and sail power.  With advancements in navigation larger ships traveled the oceans.  Packing large holds full of goods.  Making these shippers very wealthy.  Because they could transport much more than any land-based transportation system.  Not to mention the fact that they could ‘bridge’ the oceans to the New World.

This is why early cities emerged on rivers and coastal water regions.  Because that’s where the trade was.  The Italian city-states and their ports dominated Mediterranean trade until the maritime superpowers of Portugal, Spain, The Netherlands, Great Britain and France put them out of business.  Their competition for trade and colonies brought European technology to the New World.  Including a new technology that allowed civilization to move inland.  The steam engine.

Railroading transformed the Industrial Economy

Boiling water creates steam.  When this steam is contained it can do work.  Because water boiling into steam expands.  Producing pressure.  Which can push a piston.  When steam condenses back into water it contracts.  Producing a vacuum.   Which can pull a piston.  As the first useable steam engine did.  The Newcomen engine.  First used in 1712.  Which filled a cylinder with steam.  Then injected cold water in the cylinder to condense the steam back into water.  Creating a vacuum that pulled a piston down.  Miners used this engine to pump water out of their mines.  But it wasn’t very efficient.  Because the cooled cylinder that had just condensed the steam after the power stroke cooled the steam entering the cylinder for the next power stroke.

James Watt improved on this design in 1775.  By condensing the steam back into water in a condenser.  Not in the steam cylinder.  Greatly improving the efficiency of the engine.  And he made other improvements.  Including a design where a piston could move in both directions.  Under pressure.  Leading to a reciprocating engine.  And one that could be attached to a wheel.  Launching the Industrial Revolution.  By being able to put a factory pretty much anywhere.  Retiring the waterwheel and the windmill from the industrial economy.

The Industrial Revolution exploded economic activity.  Making goods at such a rate that the cost per unit plummeted.  Requiring new means of transportation to feed these industries.  And to ship the massive amount of goods they produced to market.  At first the U.S. built some canals to interconnect rivers.  But the steam engine allowed a new type of transportation.  Railroading.  Which transformed the industrial economy.  Where we shipped more and more goods by rail.  On longer and longer trains.  Which made railroading a more and more dangerous occupation.  Especially for those who coupled those trains together.  And for those who stopped them.  Two of the most dangerous jobs in the railroad industry.  And two jobs that fell to the same person.  The brakeman.

The Janney Coupler and the Westinghouse Air Brake made Railroading Safer and more Profitable

The earliest trains had an engine and a car or two.  So there wasn’t much coupling or decoupling.  And speed and weight were such that the engineer could stop the train from the engine.  But that all changed as we coupled more cars together.  In the U.S., we first connected cars together with the link-and-pin coupler.  Where something like an eyebolt slipped into a hollow tube with a hole in it.  As the engineer backed the train up a man stood between the cars being coupled and dropped a pin in the hole in the hollow tube through the eyebolt.  Dangerous work.  As cars smashed into each other a lot of brakemen still had body parts in between.  Losing fingers.  Hands.  Some even lost their life.

Perhaps even more dangerous was stopping a train.  As trains grew longer the locomotive couldn’t stop the train alone.  Brakemen had to apply the brakes evenly on every car in the train.  By moving from car to car.  On the top of a moving train.  Jumping the gap between cars.  With nothing to hold on to but the wheel they turned to apply the brakes.  A lot of men fell to their deaths.  And if one did you couldn’t grieve long.  For someone else had to stop that train.  Before it became a runaway and derailed.  Potentially killing everyone on that train.

As engines became more powerful trains grew even longer.  Resulting in more injuries and deaths.  Two inventions changed that.  The Janney coupler invented in 1873.  And the Westinghouse Air Brake invented in 1872.  Both made mandatory in 1893 by the Railroad Safety Appliance Act.  The Janney coupler is what you see on U.S. trains today.  It’s an automatic coupler that doesn’t require anyone to stand in between two cars they’re coupling together.  You just backed one car into another.  Upon impact, the couplers latch together.  They are released by a lifting a handle accessible from the side of the train.

The Westinghouse Air Brake consisted of an air line running the length of the train.  Metal tubes under cars.  And those thick hoses between cars.  The train line.  A steam-powered air compressor kept this line under pressure.  Which, in turn, maintained pressure in air tanks on each car.  To apply the brakes from the locomotive cab the engineer released pressure from this line.  The lower pressure in the train line opened a valve in the rail car air tanks, allowing air to fill a brake piston cylinder.  The piston moved linkages that engaged the brake shoes on the wheels.  With braking done by lowering air pressure it’s a failsafe system.  For example, if a coupler fails and some cars separate this will break the train line.  The train line will lose all pressure.  And the brakes will automatically engage, powered by the air tanks on each car.

Railroads without Anything to Transport Produce no Revenue

Because of the reciprocating steam engine, the Janney coupler and the Westinghouse Air Brake trains were able to get longer and faster.  Carrying great loads great distances in a shorter time.  This was the era of railroading where fortunes were made.  However, those fortunes came at a staggering cost.  For laying track cost a fortune.  Surveying, land, right-of-ways, grading, road ballast, ties, rail, bridges and tunnels weren’t cheap.  They required immense financing.  But if the line turned out to be profitable with a lot of shippers on that line to keep those rails polished, the investment paid off.  And fortunes were made.  But if the shippers didn’t appear and those rails got rusty because little revenue traveled them, fortunes were lost.  With losses so great they caused banks to fail.

The Panic of 1893 was caused in part by such speculation in railroads.  They borrowed great funds to build railroad lines that could never pay for themselves.  Without the revenue there was no way to repay these loans.  And fortunes were lost.  The fallout reverberated through the U.S. banking system.  Throwing the nation into the worst depression until the Great Depression.  Thanks to great technology.  That some thought was an automatic ticket to great wealth.  Only to learn later that even great technology cannot change the laws of economics.  Specifically, railroads without anything to transport produce no revenue.

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