TheBackShed.com

Forum Index : Off topic archive. : Engineering

Author

Message

VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 10:34am 12 Jul 2011

Copy link to clipboard

Print this post

German Bridge
Have you ever seen a river over a river?

This is a channel-bridge over the River Elbe and joins the former East and West Germany ,
As part of the unification project. It is located in the city of Magdeburg , near Berlin .

The photo was taken on the day of inauguration . . .
To those who appreciate engineering projects, here's a puzzle for you armchair engineers
. . .. and physicists.
Question:
Did that bridge have to be designed to withstand the additional weight of ship and barge traffic,
Or just the weight of the water?
Answer:
It only needs to be designed to withstand the weight of the water!
Why?
A ship always displaces an amount of water that weighs the same as the ship, regardless of how heavily a ship may be loaded.
The Magdeburg Water Bridge is a navigable aqueduct in Germany that connects the Elbe-Havel Canal to the Mittelland Canal, and allows ships to cross over the Elbe River. At 918 meters, it is the longest navigable aqueduct in the world.
The Elbe-Havel and Mittelland canals had previously met near Magdeburg but on opposite sides of the Elbe. Ships moving between the two had to make a 12-kilometer detour, descending from the Mittelland Canal through the Rothensee boat lift into the Elbe, then sailing downstream on the river, before entering the Elbe-Havel Canal through Niegripp lock. Low water levels in the Elbe often prevented fully laden canal barges from making this crossing, requiring time-consuming off-loading of cargo.

Construction of the water link was started as early as in the 1930s but due to the World War 2 and subsequent division of Germany the work remained suspended till 1997. The aqueduct was finally completed and opened to the public in 2003.

Foolin Around

VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 10:56am 12 Jul 2011

Copy link to clipboard

Print this post

THIS WILL BE INTERESTING TO PEOPLE WHO ARE MECHANICALLY MINDED!
ALSO THERE ARE OTHER REASONS WE SHOULD BE INTERESTED. BE SURE TO READ THE LAST ENTRY.

The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine is the most powerful and most efficient prime-mover in the world today. The Aioi Works of Japan 's Diesel United, Ltd built the first engines and is where some of these pictures were taken. It is available in 6 through 14 cylinder versions, all are inline engines. These engines were designed primarily for very large container ships. Ship owners like a single engine/single propeller design and the new generation of larger container ships needed a bigger engine to propel them. The cylinder bore is just under 38" and the stroke is just over 98". Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower. Total displacement comes out to 1,556,002 cubic inches (25,480 liters) for the fourteen cylinder version.

Some more facts on the 14 cylinder version:
Total engine weight: 2300 tons (The crankshaft alone weighs 300 tons).
Length: 89 feet
Height: 44 feet
Maximum power: 108,920 hp at 102 rpm
Maximum torque: 5,608,312 lb/ft at 102rpm

Fuel consumption at maximum power is 0.278 lbs per hp per hour (Brake Specific Fuel Consumption). Fuel consumption at maximum economy is 0.260 lbs/hp/hour. At maximum economy the engine exceeds 50% thermal efficiency. That is, more than 50% of the energy in the fuel in converted to motion. For comparison, most automotive and small aircraft engines have BSFC figures in the 0.40-0.60 lbs/hp/hr range and 25-30% thermal efficiency range. Even at its most efficient power setting, the big 14 consumes 1,660 gallons of heavy fuel oil per hour.

A cross section of the RTA96C:

The internals of this engine are a bit different than most automotive engines. The top of the connecting rod is not attached directly to the piston. The top of the connecting rod attaches to a "crosshead" which rides in guide channels. A long piston rod then connects the crosshead to the piston. I assume this is done so the sideways forces produced by the connecting rod are absorbed by the crosshead and not by the piston. Those sideways forces are what makes the cylinders in an auto engine get oval-shaped over time.

These guys are installing the "thin-shell" bearings.
Crank and rod journals are 38" in diameter and 16" wide.

The crankshaft sitting in the block (also known as a "gondola-style" bedplate).
This is a 10 cylinder version.
Note the steps by each crank throw that lead down into the crankcase.

:

A piston and piston rod assembly. The piston is at the top. The large square plate at the bottom is where the whole assembly attaches to the crosshead.

Some pistons and piston rods:

The "spikes" on the piston rods are hollow tubes that go into the holes you can see on the bottom of the pistons (top picture) and inject oil into the inside of
the piston which keeps the top of the piston from overheating. Some high-performance auto engines have a similar feature where an oil squirter nozzle squirts oil onto the bottom of the piston.

The cylinder deck (10 cylinder version).
Cylinder liners are die-cast ductile cast iron.
Look at the size of those head studs!

The first completed 12 cylinder engine:

[

Foolin Around

windlight
Guru

Joined: 03/03/2007
Location: Australia
Posts: 331

Posted: 11:35am 12 Jul 2011

Copy link to clipboard

Print this post

Sorry Bob I do not see your point on this one!

allan

"I like this place and willingly could waste my time in it" - (Act II, Scene IV).

VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 01:48pm 12 Jul 2011

Copy link to clipboard

Print this post

Hi Allan

As we work away at out little projects it is good to see what can be achieved by engineering, mankind has an inventive talent and I am sure will solve a lot of the problems facing humanity if greed and politics can be left out of it.

I suppose being an engineer of sorts myself it is interesting to see what is being done, and hopefully some of our members involved in the alternate energy fields will contribute some of the important developments or machines they are working on.

All the best

Bob

Foolin Around

Print this page

To reply to this topic, you need to log in.