February 1, 1918.

THE COLLIERY GUARDI AM.

229

larity in the height of the adjacent rail ends cannot
be compensated by the “ giving ” of the rails. For the
same reason, the joints of each pair of rails on the
track should be exactly opposite one another, so that
each pair of wheels will pass over both at the same
time.

For simple butted rail joints, the rail ends are sup-
ported by a sleeper (fig. 4), in which case the rails
cannot give, and the tubs will therefore jolt in passing
over the joint. With this form of laying, the joints
are preferably alternate or staggered half a rail length.
At all events, the distance between the joints on one
side and those on the other must be greater than the
wheelbase of the tubs, in order to prevent the front
wheel on one side and the rear wheel on the other from
passing over joints at the same time. Although the
absence of fishplates affords less protection against the
rails spreading, the provision of a sleeper under each
joint reduces the risk of derailing.

Special care should be bestowed on a firm bedding for
the sleepers; but, at the same time, means must be
adopted, where there is lateral rock pressure, to pre-
vent the ends of the sleepers from being squeezed so as
to affect the track gauge. This risk is prevalent in
gate roads through steeply pitched rock, if the
timbers in the floor between the upper and lower wall
are used as sleepers after packing. In such case,
pinching may be prevented by sawing through the
timber at one end.

Switches and Turntables.

The connection between main and branch tracks, by
means of switches or turntables, is a matter that
requires even greater care than track laying. Junc-
tions should never be situated—if at all possible—on
curves or steep gradients, but, on the latter, a short
section of road should be levelled for the junction. As
the strain on rails, sleepers, and their connections is
particularly heavy in junctions, all these members
should be made extra strong.

Turntables.—These are mostly plates of cast iron or
cast steel, with circular central ribs and segmental
corner ribs enabling the tubs to be turned with ease.
Tables on ball or roller bearings have not made much
headway in mines, owing to the trouble and expense
of upkeep, and the fact that even the largest tubs can
be turned on the ordinary tables without difficulty.

The turntable is carefully bedded on a wooden frame,
connected with the rail tracks by sleepers. Unless the
bedplate can be connected to the rails by fishplates,
etc., there is always a good deal of jolting as the tubs
run on and off the tables, whereby the latter are liable
to be forced out of place and cause derailment. This
difficulty is specially apparent where the road floor
shows a tendency to creep, the rails being forced up at
one time and the turntable at another, the heavy
impact of the tubs then causing frequent smashing of
the tables. On this account, the use of the simple
turntable, with its small amount of room and easy
installation, has to be replaced by the more expensive
switch in main roads and rope haulages.

In another form of turntable, the ribs are replaced
by grooves to take the tub wheel flanges, the tub
having to be lifted to get it on to the rail track. In
some cases, the rails of the main track are continued
across the turntable, guard rails, of wood or iron,
being provided to leave a groove for the wheel flanges.
With this form, however, there is much difficulty in
turning the tubs on the table; and, whilst they are
easily run on, there is much heavy jolting, which
increases the cost of upkeep. In the case of double-
track tables, the defects are still greater.

These difficulties, however, can be largely overcome
by the use of a ribbed turntable, which can be con-
nected to the rails and other tables by fishplates. Such
a table is shown in figs. 5 and 6; whilst fig. 7 illustrates
a double track crossing. The table is provided at the
corners a with recesses b for the wheel flanges, and with
bolt holes c for the fishplates. The space d inside
the central rib is made hollow in order to reduce the
weight. For inclines and horse haulage, 0-8 in. metal
is used, and 1-4 in. metal for locomotive haulage, the
weight of the table being 3 cwt. in the one case and
5 cwt. in the other.'

This (Peisen) turntable has been found satisfactory in
the Aachen pits, where it is extensively used for loco-
motive, rope and horse haulage systems, self-acting
inclines, and gate roads, replacing expensive switches
in many cases.

To prevent or reduce the shock caused by the
oncoming tubs, flat pieces of iron are laid on the table
at the rail extensions, being held in position by pins
fitting into holes in the table, and removed for switch-
ing on to a branch track.

With all ribbed turntables it is necessary to see that
the guide ribs are not higher than the depth of the
wheel flanges; otherwise the tub will drop down heavily
on the table and damage it, whilst the tub will have
to make a jump on to the rails in running off the table.

A very useful auxiliary for haulage and goaf packing
operations, and especially in gate roads of thick level
seams, is the ramp turntable of Klemp-Schultze and
Company, Dusseldorf, which enables a branch track to
be connected up to a main track anywhere, without
having to interrupt the continuity of the latter. For
this purpose, it is sloped downward towards all four
corners, thus enabling the tubs to be run up easily.

Switches.—These may have either fixed or movable
points, the former being largely used on putting and
horse haulage roads, on account of their simplicity.
They require, however, the tubs to be slowed down at
the junction, and each tub to be pushed by hand on
to the desired track.

A method that is very useful, and has no movable
parts, can be recommended for inclines where the rock
pressure is heavy. It consists in laying three rails to
exact track gauge, and only widening out the line to
a full double track at fixed meeting places. It can
also be employed where a double track has to be carried
through a barrier door; and complicated junctions—
such as from double track cross headings to double
track bottom roads—can be simplified by joining the

two middle rails into one, so that the junction repre-
sents a crossing of three rail tracks.

Switches with movable points or frogs are almost
entirely confined to mechanical haulage work. The
two adjacent rails of the main and branch tracks are
connected by means of a solid nose block, whilst swing
points, suitably curved and tapering down to fine
edges, serve to divert the tubs from the main to the
branch. To prevent derailment, which is very liable to
occur at the points, guard rails are provided on the
outer rails, to keep the wheels on the track. In many
cases the two swing points are connected together by
cross rods, and are made extra long to facilitate switch-
ing, in which event they must also be made addition-
ally strong, to prevent tilting, by bolting flat strips to
the webs.

Where the branch is a single track, the line should be
laid with facing points, so that the tubs run straight
on to the branch; and on tracks where chiefly full tubs
are carried on the one journey and empty ones on the
return, it is better to arrange for the full tubs to run
straight through at both the terminal switches rather
than divert them at these points.

Since regular maintenance of traffic greatly depends
on the switches in main haulage roads, these switches
must be laid with special care. The sleepers must be
set close together, particularly under the rail inter-
sections. To prevent any relative shifting of the
different members of the switch, and thereby remove a
frequent source of trouble, the switch as a whole should
be mounted on as small a number of bedplates as pos-
sible, especially on floors with a tendency to creep,
since this arrangement greatly facilitates the occasion-
ally necessary lowering of the entire level of the switch.

COKE OVEN MANAGERS* ASSOCIATION:
MIDLAND SECTION.

A meeting of members of the Midland section of the
Coke Oven Managers’ Association was held at Shef-
field on Saturday last, January 26, when a paper by
Messrs. B. Wilson Haigh and Harold Lamb, entitled
“ Notes on the Comparative Values of Coke Oven
Crude Benzols ” (see page 225 of this issue) was read.

Mr. J. W. Lee (president of the section) said the
paper was one which he was sure would prove of great
interest to the members of the association. It was a
subject that they had often had before them in the
past, and which they were likely to have before them
still more in the future. As long as the Coke Oven
Managers’ Association existed, there was always likely
to be something new that could be said about benzol;
he was sure that those of the members who had had the
opportunity of reading the advance copies of the paper
that had been circulated, would agree with him that
the subject had been dealt with in a manner that
would prove of the greatest benefit to the industry.

Discussion.

The President, in inviting discussion, said that the
paper was typical of what should always obtain in the
working of coke oven plants — close co-operation
between the manager and the chemist; and the advan-
tages that were likely to accrue from such association
were shown in the results obtained by the writers of
the paper.

Mr. J. Thorpe (Barugh) said, with regard to the
effect of a percentage of water on absorption, he could
not agree with the conclusion that when the water rose
to a percentage of 2J, the efficiency dropped to 35
per cent, as a consequence. He thought that that was
not altogether the fault of the water, but that there
had been some other conditions where the water had
been allowed to get into the absorbing plant through
the hot gases. If the remainder of the plant was pro-
vided with an efficient heater, and an efficient still, in
his opinion, that loss would not have occurred. Another
point on which he differed from the authors was their
statement that in benzol absorption they preferred to
pass through their scrubbers only the amount of oil
that they passed through the stills. In his opinion,
the better way was to keep the scrubbers going with
plenty of oil, even if it was not passed through the
still, but to keep the oil circulating, even though the
still could not cope with it all, and though the heaters
and coolers did not deal with it sufficiently for further
absorption. He also disagreed with the statement that
the benzol which was absorbed was nearly always of the
same value—that it would have the same amount of
benzol, the, same amount of toluol, or naphtha—
because he believed that fractional absorption
occurred. In summer time, for instance, with the
warmer gas, there would be absorbed nearly all the
toluene from the naphtha. Perhaps further light
would be thrown on this by others; but certainly, in his
own experience, while he did not lose toluol or naphtha,
he certainly did lose benzol during the summer season,
or, at any rate, some of the benzol. His principal
grievance, however, was in respect to the authors’
graph, which attempted to show the comparative values
of benzols of various strength. He took it that in
every case they had distilled them at 200 degs., and
in each case the material taken was creosote. Now, it
was obvious that there was far more creosote in that
benzol, and the authors were distilling off material
which should remain behind. The percentage of
material which was distilled between 190 and 200 degs.
made a very serious error, and from his experience he
was of opinion that it gave too high a value on the
low-grade material, taking the material at 45 or
46 degs.

Mr. T. B. Smith (Stocksbridge) said that, in carry-
ing out some experiments at different periods of the
year he found that, on the coldest days, the percentage
of toluene and naphtha rose and benzol dropped,
whereas in the summer the benzol was 90 per cent.,
and the toluene and naphtha down to 10 per cent. He
compiled a curve on the temperature, and it tended to
prove Mr. Thorpe’s view that the temperature and

atmosphere factors made it impossible to say that the
composition of the crude benzol always remained the
same.

Mr. M. E. Nicklin (Wombwell) believed there was
sufficient evidence to show that the authors’ conclusion
regarding water contained in the absorbing oil was
very wide of the mark. In his own experience, when
breakdown had occurred, he had absorbing oil passing
through the scrubbers containing as much as 45 per
cent, of water, and the make of benzol had been quite
75 per cent, of the ordinary make. Then, with regard
to the saturation of the oil, the authors did not advo-
cate a low degree of saturation, and gave the figure
2 per cent. He would like to know by what test that
figure was.arrived at. Different people had different
ways of testing their oil, and. by one test a figure of
2 per cent, might be obtained, which, by another test
by better fractionating apparatus, might give 4 per
cent.; and two men working, one at 2 per cent, and
the other at 4 per cent, saturation, might have the
same oil, the difference being simply in the method of
carrying out the test.’ That was a matter upon which
some system of standardisation was much needed. A
further point, which did not bear out his own experi-
ence, was in regard to the rectification of the crude
benzol. Taking the figure as 65 per cent., when work-
ing on a large scale, it gave something like 14 or 15
per cent, creosote oil. Allowing 5 per cent, loss in
washing, it gave a yield of 80 per cent, saleable pro-
ducts, which in his opinion, was rather too high an
estimate. He would like a little information showing
how the authors actually arrived at that 14 per cent,
creosote oil, and if it included naphthalene, in which
case, of course, it would reduce the percentage.

Mr. W. Green agreed with Mr. Nicklin as to the
need for a standard test in regard to saturation. In
regard to the increase of creosote in the benzol, the
authors stated this depended to some extent on the
coal used, but he would suggest that it depended more
on the conditions under which the still was working,
and the temperature at which it was worked. Then
again, in Table 3 there were comparisons of the benzol
test and the flask test, and also the rectifying pro-
ducts, but he supposed that in this percentage of
material there would be a certain amount of paraffin.
In this connection, however, the matter could have
been settled better by a quantitative estimate of the
carbon disulphide in the original crude benzol, and also
in the rectified product, and by some statement as to
the amount of paraffin present. Then, with reference
to the influence of temperature on composition, he
thought that hardly sufficient data was given to afford
much information. He would also like to ask if any
members had any experience of centrifugal washers in
connection with benzol recovery, and exactly what
advantages they were supposed to give in the working
of the plant.

Mr. E. Millington (Rockingham) said Mr. Green
had covered the point he was going to raise with regard
to paraffin. With regard to the effect of a washing
operation, it was necessary to know the washing test,
and also the amount of paraffin before one could start
to draw charts which would show any comparative
value whatever. He himself had found in various pur-
chased benzols, not only paraffins, but also other pro-
ducts, which, even at 60 to 65 per cent., made crude
benzols practically useless.

Mr. T. P. Carr (Waleswood) said, with reference to
the advice that the temperature of the scrubbing oil
should not fall below the temperature of the gas pass-
ing through the scrubbers, that very often one could
not get the temperature of the gas as low as desirable.
For instance, where all the cooling water had to be
re-cooled in a wooden tower, one could not, in summer
time, get the gas at a sufficiently low temperature—
often not below 30 degs. In such cases it would never,
in his opinion, pay to keep the oil temperature a few
degrees above the gas temperature. It would be much
more profitable to have a large pre-heater to the still
for creosote, and to ensure taking out all the water
from the creosote, and circulate plenty of creosote
round the scrubbers. It did not matter whether that
got the water in; there should be a heating apparatus,
before the still, large enough to deal with that, other-
wise they would recover very little benzol. He could
not agree with the conclusions by Mr. Diamond quoted
by another speaker; his experience had been the same
as that of Mr. Nicklin—he had 40 or 50 per cent, of
water in the oil, and still recovered the same benzol.
Probably Mr. Diamond’s circulation had been very
small, and the oil had contained a little water, which
had affected the volume of water going through the
scrubber, or there must have been some other reason
for quoting such high figures; but he himself could not
see how such figures were borne out in any way. With
regard to the oil going into the still, he quite agreed
that it should never be below 110 degs. Water could
not be kept out from the oil at a lower temperature
than that.

Mr. Nicklin said another point which had interested
him was with regard to the temperatures of the oil
entering and leaving the still. Personally, he did not
think it so much a question of fixing definite tempera-
tures for these two points. It was a matter of bear-
ing in mind what they were out to obtain. In the
first place, they were out to strip the gas as much as
possible—100 per cent, if possible—and then, having
got the benzol from the gas, the next point was to get
it out of the oil as efficiently as possible; and, of course,
the question of temperature came in with regard to the
deposition of water in the still, and so long as the
outlet temperature was kept above 100 degs. Cent., he
did not think, with a fair steam pressure—anything
over 70 lb.—there was much danger of deposition of
water in the still. He had seen plants working at a
temperature as high as 135 degs. Cent., and at that
temperature producing 65 per cent. With a reduction
in temperature of about 15 degs., the oil was very
badly cracked—pitchified, so to speak—and but for the
fact that they had two heaters (a stand-by) it would
have resulted in considerable losses while the heater