Rack_railway

Rack railway

From Wikipedia, the free encyclopedia

Rack railway track using the Lamella system rack.

A

cog railway

,

pens and rails railway

,

rack-and-pinion railway

or

rack

railway

is

a

railway

with

a

toothed

rack

rail

,

usually

between

the

running

rails

. The

trains

are fitted with one or more

cog wheels

or

pinions

that

mesh with this

rack rail

. This allows the trains to operate on steep

gradients

.

Schneeberg cog railway steam locomotive, with tilted boiler, on level

track.

Most rack railways are

mountain railways

, although a few are

transit

railways

or

tramways

built to overcome a steep

gradient

in an

urban

environment.

The first cog railway was the

Middleton Railway

between

Middleton

and

Leeds

in

West Yorkshire

,

England

,

UK

, where the first commercial

steam

locomotive

,

Salamanca

, ran in 1812. This used a

rack and pinion

system

designed and patented in 1811 by

John Blenkinsop

.

[1]

functioning of the

rack and pinion

.

The first mountain cog railway was the

Mount Washington Cog Railway

in

the

US

state of

New Hampshire

, which carried its first fare-paying

passengers in 1868 and reached the summit of

Mount Washington

in 1869.

The first mountain rack railway in

Europe

was the

Vitznau-Rigi-Bahn

on

Mount Rigi

in

Switzerland

, which opened in 1871. Both lines are still

running.

Rack systems

A number of different rack systems have been developed. Today, the

majority of rack railways use the Abt system.

Different

rack

systems:

from

the

left,

Riggenbach

,

Strub

,

Abt

and

Locher

.

Blenkinsop

Thinking that the friction of metal wheels on metal rails would be too

low,

John Blenkinsop

built his

locomotives

for the

Middleton Railway

in

1812 with a 20 teeth, three feet diameter cog wheel (pinion) on the left

side that engaged in rack teeth (two teeth per foot) on the outer side

of

the

rail,

the

metal

edge

rail

with

its

side

rack

being

cast

all in one piece, in three feet (one yard) lengths.

All other rack systems place the rack rail halfway between the running

rails.

Blenkinsop rack and pinion with teeth on outer side of one rail only -

see better image on

Middleton Railway

page.

Stephenson

George

Stephenson

grouped

the

steep

gradients

on

either

side

of

Rainhill

and from

Liverpool

down to the wharfs, just in case

cable haulage

was

necessary. In the event, only the wharf line needed cable haulage for a

few decades.

[

edit

] Marsh

The first successful rack railway in the US was the

Mount Washington Cog

Railway

,

developed

by

Sylvester

Marsh

.

Marsh

developed

and

tested

his

rack

system

and

on

10

September

1861

he

was

issued

a

US

patent

for

his

invention.

The Mount Washington railway opened in 1869, using Marsh's central rack

which employed parallel wrought iron angle bars, connected by regularly

spaced pins. The pinion wheels on the locomotives had deep teeth that

ensure that at least two teeth are engaged with the rack at all times -

this measure helps reduce the possibility of the pinions riding up and

out of the rack.

[1]

Riggenbach

The

Riggenbach

rack

system

was

invented

by

Niklaus

Riggenbach

working

at

about the same time as, but independently from Marsh. Riggenbach was

granted a French patent in 1863 based on a working model which he used

to interest potential Swiss backers. During this time, the Swiss Consul

to the United States visited Marsh's Mount Washington Cog Railway and

reported back with enthusiasm to the Swiss government. Eager to boost

tourism in Switzerland, the government commissioned Riggenbach to build

a

rack

railway

up

Rigi

Mountain

.

Following

the

construction

of

a

prototype

locomotive and test track in a quarry near

Berne

, the

Vitznau-Rigi-Bahn

opened on 22 May 1871.

[1]

The Riggenbach rack system

The Riggenbach system is similar in design to the Marsh system. It uses

a

ladder

rack

, formed of

steel

plates

or

channels

connected by

round

or

square

rods

at

regular

intervals.

The

Riggenbach

system

suffers

from

the

problem

that

its

fixed

ladder

rack

is

more

complex

and

expensive

to

build

than the other systems.

Following the success of the Vitznau-Rigi-Bahn, Riggenbach established

the

Maschinenfabrik

der

Internationalen

Gesellschaft

für

Bergbahnen

(IGB)

[1]

- a company that produced rack locomotives to his design.

Strub

The

Strub

rack

system

was

invented

by

Emil

Strub

in

1896.

It

uses

a

rolled

flat- bottom

rail

with rack teeth machined into the head approximately

100 mm apart. Safety jaws fitted to the locomotive engage with the

underside of the head to prevent derailments.

[1]

The best-known use of the Strub system is on the

Jungfraubahn

in

Switzerland.

[1]

It is the simplest rack system to maintain and has become

increasingly popular

[

citation needed

]

.

The Strub rack system

Abt

The

Abt

system

was

devised

by

Roman

Abt

,

a

Swiss

locomotive

engineer.

Abt

worked for Riggenbach at his works in

Olten

and later at his IGB rack

locomotive company. In 1885 he founded his own civil engineering

company.

[1]

During

the

early

1880s,

Abt

worked

to

devise

an

improved

rack

system

that

overcame the limitations of the Riggenbach system. In particular, the

Riggenbach

rack

was

expensive

to

manufacture

and

maintain

and

the

switches

were complex. In 1882 Abt designed a new rack using solid bars with

vertical

teeth

machined

into

them.

Two

or

three

of

these

bars

are

mounted

centrally between the rails, with the teeth offset. The use of multiple

bars

with

offset

teeth

ensures

that

the

pinions

on

the

locomotive

driving

wheels are constantly engaged with the rack. The Abt system is cheaper

to build than the Riggenbach because it requires a lower weight of rack

over

a

given

length.

However

the

Riggenbach

system

exhibits

greater

wear

[1]

resistance than the Abt.

Abt rack system

Abt rack system

The

first

use

of

the

Abt

system

was

on

the

Harzbahn

in

Germany

which

opened

in 1885.

[1]

The pinion wheels can be mounted on the same axle as the rail wheels (as

in

the

picture

at

right),

or

driven

separately.

The

steam

locomotives

on

the

Mount

Lyell

Mining

and

Railway

Company

had

separate

cylinders

driving

the pinion wheel.

Locher

The Locher rack system,

invented by

Eduard

Locher

, has

gear

teeth cut in

the sides rather than the top of the rail, engaged by two cog wheels on

the locomotive. This system allows use on steeper grades than the other

systems,

whose

teeth

could

jump

out

of

the

rack.

It

is

used

on

the

Pilatus

Railway

.

Locher rack system

Locher set out to design a rack system that could be used on gradients

as steep as 1 in 2 (50%). The Abt system - the most common rack system

in

Switzerland

at the time - was limited to a maximum gradient of 1 in

4 (25%). Locher showed that on steeper grade, the Abt system was prone

to the driving pinion over-riding the rack causing potentially

catastrophic derailments, as predicted by Dr. Abt. To overcome this

problem and allow a rack line up the steep sides of

Mt. Pilatus

, Locher

developed a rack system where the rack is a flat bar with symmetrical,

horizontal teeth. Horizontal pinions engage the centrally-mounted bar,

both driving the locomotive and keeping it centered on the track.

Locher Rack system (seen from above)

This

system

provides

very

stable

attachment

to

the

track,

also

protecting

the

car

from

toppling

over

even

under

the

severest

cross

winds.

Such

gears

are also capable to lead the car, so even flanges on running wheels are

optional. The biggest shortcoming of the system seems that the ordinary

railway

switch

is

not

possible

and

a

transfer

table

or

other

complex

device

must be used where it is needed to branch the track.

Following tests, the Locher system was deployed on the Pilatus Railway

which opened in 1889. No other public railway uses the Locher system,

although

some

European

coal

mines

use

a

similar

system

on

steeply

graded

underground lines.

[1]

[

edit

] Lamella

The Lamella system (also known as the Von Roll system) was developed by

the

Von

Roll

company

after

the

rolled

steel

rails

used

in

the

Strub

system

became unavailable. It is formed from a single blade cut in a similar

fashion to the Abt system but typically wider than a single Abt bar. The

Lamella

rack

can

be

used

by

locomotives

designed

for

use

on

the

Riggenbach

or the Strub systems and some railways use rack from multiple systems.

The

St. Gallen Gais Appenzell Railway

in Switzerland has sections of

Riggenbach, Strub and Lamella rack.

[1]

Most of the rack railways built from the late 20th century onwards have

used the Lamella system.

[1]

Most of the rack railways built from the late 20th century onwards have

used the Lamella system.

[1]

Joint between Riggenbach and Strub

Rack-and-adhesion systems / Pure rack systems

Rack-and-adhesion

systems

use

the

cog

drive

only

on

the

steepest

sections

and

elsewhere

operate

as

a

regular

railway.

Others,

the

steeper

ones,

are

rack-only. On the latter type, the locomotives' wheels are generally

free-wheeling and despite appearances do not contribute to driving the

train. In this case the racks continue also in the horizontal parts, if

any.

Fell

The

Fell

mountain

railway

system

is

not

strictly

speaking

a

rack

railway

since there are no cogs with teeth. Rather, this system uses a smooth

raised centre rail between

the two running

rails on steep

lines which is

gripped

on

both

sides

to

improve

friction.

Trains

are

propelled

by

wheels

or braked by shoes

pressed horizontally

onto the centre

rail, as well as

by means of the normal running wheels.

[

edit

] Switches

Railroad switch

at rack railway (

?trbské Pleso

,

Slovakia

)