PB15 (1924) Class

Total Number of Engines Built 30
First Engine Built 1925
Last Engine Built 1926
First Engine Written Off 1967
Last Engine Written Off 1970
Number of Engines in Class on the Books as at:
31/12/20 31/12/30 31/12/40 31/12/50 31/12/60 31/12/66 31/12/67 31/12/68 31/12/69 31/12/70
30 30 30 30 30 29 18 7
Number of Engines in Class in Service as at:
31/12/67 31/12/68 7/10/69
18 6 4


This class was built to overcome an acute shortage of motive power on lines that could not take C16 or heavier classes of locomotives. The design was based on the earlier successful 1899 engines. Although fitted with Walschaert valve gear and larger tenders, they surprisingly retained saturated boilers. They were referred to as PB15 1924 to distinguish them from the earlier series. In later years, at least, the year was rarely shown on locomotives.

They were used as “Mail” engines in areas where anything heavier was prohibited. Until 1935, they worked the Cairns Mail over its final leg from Innisfail to Cairns. Before the introduction of 60 ton DEL, they were used on the “Westlander” beyond Roma. Together with a C17, they double headed this train far as Charleville. From there a single PB15 hauled it for the remainder of the journey to Cunnamulla.

Similar to the older style PB15s, they were also used on branch line mixed and goods trains and as yard shunting engines.

Several were attached to Wooloongabba where they were used on suburban passenger trains and Southport Expresses.

The first engine to be written off was N°740 in 1967.

The last engines in service were N°732, N°741 and N°745 at Mackay and N°750 at Ipswich.


Walkers – Walkers Limited, Engineers, Maryborough, Qld

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Technical Details
Wheel Arrangement4-6-0
Cylinders (diameter x stroke) ins.15 X 20
Coupled Wheels diameter ins.48
Rigid Wheel Base9' 9"
Length47' 6"
Height over smoke stack12' 0¼"
Axle Load8
Boiler Pressure - psi.160
Heating Surface - tubes792
Heating Surface - Total sq. ft.872
Grate Area - sq. ft.13.1
Weight - Adhesive24.9
Weight - Engine34.0
Weight - Tender28.1
Coal Capacity - tons4
Water Capacity - gallons2500
Tractive Effort - lbs. (85%)12000 (80%)
Factor of Adhesion4.65
Valve GearWalschaert & D Valve
Westinghouse Pump8 X 8½
Brake ValveNo4
Class Roster