logotype

Specifications

A relatively modern design of locomotive (loosely developed from the earlier Class D49 4-4-0 type) it has piston valves and three cylinders. The inside cylinder is driven by the Gresley Conjugated Valve Gear (a development of the Walschaert valve gear) by which the valve for the centre cylinder has its motion derived from the two outer cylinders. The outside cylinders drive the centre axle and the inside cylinder drives the front axle. It features a round topped boiler, with the characteristic gracefully curved Gresley running plate, with the nameplate positioned on the splasher over the centre driving wheels.

Because of its Great Eastern heritage some of the locomotives were fitted with air brakes in addition to the more customary vacuum brakes. For those so fitted the air pump was on the right hand side of the locomotive adjacent to the smoke box, with the air brake hose on the buffer beam next to the vacuum hose. Indeed, there were three varieties of braking system, ostensibly as follows although variations occurred as time progressed:

Loco Brake

Train Brake

Locomotives

Air

Air or Vacuum

61600 - 61615

Steam

Vacuum

61616 - 61642

Vacuum

Vacuum

61643 - 61673

As is often the case there were more than one variation of the class, such being designated as B17/1, B17/4, B17/5 or B17/6. Note that the B17/5 variation was purely cosmetic with a streamlined appearance.

The original design (B17/1) required a relatively light axle loading (for the lines in East Anglia, where the class were destined to be employed) while at the same time having the necessary power to haul the increasingly heavy trains being introduced at the time. Small GE style tenders were initially required due to the short turntables then extant on the former GE section (1928). Due to in initial teething problems numerous design changes were implemented to improve the draughting, the springing and, in particular ,the frames which in their original form were prone to cracking.

Later designs includied these improvements and also saw the introduction of the larger LNER style tenders.  These locos were designated B17/4’s and were intended for use on longer journeys on the former GC section where the civil engineering restrictions of East Anglia did not apply. As the track in former GE section was improved and bridges strengthened (along with the introduction of larger turntables) the low weight and short wheelbase of the original class members became less a factor and allowed the use of the LNER style tenders throughout the system.

The final improvement was the introduction of the 100A diagram boiler defining the B17/6’s. Some of the class were fully rebuilt by Thompson as a two cylinder locomotive to form the B2 class, which was essentially a B1 with large driving wheels.

Class Details (for all B17 types)

Item

Value

 

Item

Value

Wheels

4-6-0

 

Superheated

Yes

Piston diameter

17 1/2”

 

Valve gear

Gresley conjugated

Piston stroke

26”

 

Valve type

Piston

Driving wheels

6’ 8”

 

Cylinders

Three

Loco weight

77 tons 5 cwt.

 

Driving position

Left side

 

Class Details (for the B17/1 variant)

 

Item

Value

 

Item

Value

Traffic

Mixed Traffic

 

Introduced

1928

Boiler pressure

180 psi

 

BR power class

4MT

Tractive effort

22,485 lb.

 

GE Loco tender

39 tons

 

 Class Details (for the B17/4 variant)

 

Item

Value

 

Item

Value

Traffic

Mixed Traffic

 

Introduced

1936

Boiler pressure

180 psi

 

BR power class

4MT

Tractive effort

22,485 lb.

 

LNER Loco tender

52 tons

 

Class Details (for the B17/6 variant)

 

Item

Value

 

Item

Value

Traffic

Mixed traffic

 

Introduced

1943 / 1947

Boiler pressure

225 psi

 

BR power class

5P4F

Tractive effort

28,555 lb.

 

Loco tender

39 tons 6 cwt. (GE) 52 tons (LNER)

 

Class Details (for the B2)

 

Item

Value

 

Item

Value

Wheels

4-6-0

 

Introduced

1945

Traffic

Mixed Traffic

 

BR power class

5P4F

Boiler pressure

225 psi

 

Superheated

Yes

Piston diameter

20”

 

Valve gear

Walschaert

Piston stroke

26”

 

Valve type

Piston

Driving wheels

6’ 8”

 

Cylinders

Two

Tractive effort

24,865 lb.

 

Driving position

Left side

Loco weight

73 tons 10 cwt.

 

Loco tender

46 tons 12 cwt (NE) 52 tons (LNER)