198 Molesworth’s pocket-book
Hepobt of German Railway Union—continued.
LOCOMOTIVES.
Six-coupled engines are chiefly used on long gradients
above 1 in 40 and 4-coupled on short gradients.
Ratio of working cost does not differ much in 6 and 8
coupled engines, for ratio of tractive power.
Higher pressure than 150 lbs. is undesirable.
Majority of railways approve of connecting springs by
lever, but advantages not marked.
Sliding axles recommended on 8-coupled engines of long
wheel base and on shunting engines.
Two-wheel bogies, “ Bissel ” and “ Nowotny ” systems,
considered preferable to 4-wheeled bogies.
Bogies considered to give greater speed on straight and
greater safety on curves. “ Nowotny ” system preferred to
“ Bissel.”
Mean value of experiments gives resistance -0039 to -0044
of the load (8-74 to 9-85 lbs. per ton).
Steel boilers are not generally recommended.
Pressure test of little value except as to tightness.
Steam dome is necessary where gradients are severe aad
variable.
Gussets generally preferred for staying front of fire-box.
General opinion that molecular changes do not take place
in boilers.
No satisfactory plan for obviating grooving and pitting.
Steel tubes not recommended.
Water treated with lime and caustic soda in closed tanks
prevents scale. Hot jets for washing out suggested.
Stay bolts generally preferred to crown bars for fire-
boxes.
Steel and iron fire-boxes not approved.
Average radius for corners of fire-box about 7| inches.
Cast-iron fire-bars present no advantage; wrought-iron
best for coke.
Steel preferred for axles and tires.
Use of phosphor bronze for beatings doubtful.
Lubricants for flanges going round curves advisable ; either
grease, petroleum, or water.
In large cylinders it is advantageous to pana the piston rod
through the end of the cylinder cover.
Bessemer mild steel suitable for connecting and coupling
rods, cranks, &c.