oo. 
yr 
‘@ 
54 W. H. WARREN. 
experiment. The boilers are similar in all respects but 
larger than those for the passenger engines. 
The tenders are carried on double bogie trucks, necessi- — 
tated by the large capacity and sharpness of many of the 
curves on the mountain lines of these railways. Both 
engine and tender are thoroughly equipped with Westing- 
house automatic and hand screw brake-gear, and. every 
provision has been made for large and efficient wearing 
surfaces, dust shields and lubricating appliances. 
The class of engine used in the suburban passenger ser- 
vice has also been improved by the Commissioners, and 15 
engines of what is known as the ‘‘M”’ class, commenced 
service in 1891. They are of the four-wheel coupied type, 
and a four-wheel bogie at the front end and single radial 
axle at the rear end. 
Owing to the heavy passenger traffic that has now to be 
carried over the suburban lines during the busy hours of 
the morning and evening, it is considered advisable to run 
trains longer than those hauled by the present ‘“‘ M”’ class 
engines, and therefore a more powerful suburban tank 
engine is now being delivered on order. They will be known 
as the ‘‘S’’ class, and be capable of hauling at least 257 
more load than has previously been dealt with. They have 
outside cylinders fitted with balanced slide valves, operated 
by Allen’s straight link motion, controlled by screw revers- 
ing gear. The boilers are similar in design, and constructed 
of the same class of materials as those for the passenger 
and heavy goods engines. Side tanks and coal bunkers are 
arranged with gangways for access to the enginemen’s 
platform in the same way as the “‘M”’ class. The follow- 
ing schedule gives the main dimensions of the four modern 
engines above alluded to :— 
