INTRODUCTION

One of the principal features of modern rail car operations is the ability for a number of vehicles to be controlled by a single driver under some form of multiple unit (MU) control. Multiple unit operation also permits rail car trains to be worked as a single unit to a distant junction station where they can be divided to work to different destinations as smaller capacity trains. The return working results in the amalgamation of trains at the junction to be worked as a single unit to a central destination. This form of working results in a significant saving in crew costs and train paths as well as providing through working to and from remote locations without the necessity of changing trains. This form of working was first implemented on the Northern Tablelands Express and the Canberra-Monaro Express services in the mid-1950's and still persists today with the Northern Tablelands Xplorer (dividing at Werris Creek for Armidale and Moree) and the Canberra Xplorer (dividing at Goulburn for Canberra and Griffith). Extensive use of this feature was also made on the Riverina Express in the early 1970's but recurrent mechanical failures with the rolling stock being used resulted in the service being withdrawn.

EARLY RAIL MOTORS

The early rail motors of the 42-Foot or CPH Class were fitted with mechanical transmissions and this limited any attempt to provide multiple unit control, the motor having to run around any attached trailer at a terminus for the return journey. Likewise two or more motors operating together required a driver in each vehicle (with the leading driver having control of air brake). Rail Motor No.38, the 100 Class and the 400 Class vehicles, although fitted with hydraulic transmissions when built, were not given any form of multiple unit capability.

In NSW, multiple unit control was first introduced when the CPH Class rail motors received new Detroit Diesel engines and Twin Disc hydraulic transmissions from 1945 onwards. From 1949, the five CTH Class rail motor trailers were also fitted with a driving cab and multiple unit controls at one end, enabling any attached CPH power cars to be driven from the trailer. Concurrent with this upgrading work, the new 600 Class 2-car diesel units, that entered service in 1949, were built with multiple unit control from the outset. All vehicles subsequent to the 600 Class were provided with multiple unit control when built.

BASIC MULTIPLE UNIT CONTROL

The basic multiple unit control functionality is provided by an electro-pneumatic system with magnet valves on each vehicle admitting or exhausting air pressure to activate or deactivate a specific piece of equipment such as the throttle, direction control or transmission function. This is achieved by having a continuous electrical circuit (called a "train wire") running throughout the length of the train to connect all magnet valves performing a particular function to the driver's control stand. Movement of the driver's control levers provide power to the "train wire" activating all magnet valves throughout the train simultaneously. Connectivity between individual vehicles on the train is facilitated with flexible electrical jumper couplings. Other functions provided throughout the train by "train wires" include the Guard's bell, passenger alarm, warning systems, lighting control and in some instances door opening, closing and locking. Train brakes, main air reservoir and in some classes, the pneumatic throttle control, are provided by continuous air pipes throughout the length of the train.

Later vehicles of the Endeavour, Xplorer and Hunter Class rail cars are fitted with multi-function couplers at the outer ends. These couplers provide both electrical and pneumatic connections between vehicle sets. They also facilitate automated one-man coupling and uncoupling from the driver's cab without the necessity of physically carrying out the coupling process. German-designed Scharfenberg couplers are used on the Endeavours and Xplorers while Swedish-made Dellner couplers are used on the Hunter Class.

Jumper
A Typical MU Jumper Cable
Photo: Bruce Agland

Dellner
Dellner Multi-function Coupler
Photo: Bruce Agland

 

Scharfenberg
Scharfenberg Multi-function Coupler
Photo: Bruce Agland

42-FOOT RAIL MOTORS

The CPH Class multiple unit system provides electro-pneumatic control of the direction and transmission, while the throttle is fully pneumatic in operation. In this class the control of the transmission "lockup" feature is handled manually by the driver and the multiple unit system provides an interlock to ensure the engine is at idle before permitting direct drive to be selected. The throttle control consists of a continuous air pipe throughout the train and movement of the throttle lever admits air pressure to the pipe causing the throttle actuator on all engines to move. Being pneumatic in operation there is a time lag as air pressure moves along the train pipe and this is one of the factors limiting a 42-Foot Rail Motor consist to a maximum of five cars. The CPH and CTC Classes are limited to multiple unit working within the classes. Another limiting factor for this is that these vehicles have a positive earth electrical system, while all of the later units have a negative earth system.

CPH controls
CPH Class Control Panel
Photo: Bruce Agland
 
The driver's controls are (left to right) handbrake, direction control, transmission control, master control key, throttle and WL brake valve.

400 controls
400 Class Control Panel
Photo: Bruce Agland
 
The driver's controls are (left to right) direction control, transmission control, master control key, throttle, SEM brake valve and handbrake.

RAIL MOTOR No.38, 100 CLASS AND 400 CLASS

Other than the straight air brake, No.38 and the 100 and 400 Classes were not fitted with any form of multiple unit controls. The passenger alarm and guard's bell were, however, carried through from the trailer cars to the power cars by a jumper cable. The 100 Class was essentially a locomotive and operated singly when hauling a set of trailer cars. Around the time multiple unit controls were being fitted to the CPH Class and trailers, No.38 and the 400 Class were operating in areas where there was limited use of trailer cars and the necessity for MU capability was not required.

600 CLASS RAIL MOTORS

The 600 Class multiple unit system provides electro-pneumatic control of the direction and transmission, while the throttle is pneumatic in operation. The 600 Class throttle is fitted with an electro-pneumatic (EP) feature that is used when trains consisting of more than one 2-car set are worked together. The EP throttle works in a similar manner to the EP brake with a master controller activating magnet valves on each power car's throttle. This prevents any "lag" in the working of the throttle throughout the train. Transmission "lockup" is automated, however, the direction control and transmission engagement are initiated from the driver's control stand and activated by magnet valves. Because of the pneumatic and EP throttle, the 600 Class were limited to multiple unit working within the class only. When the five 600 Class sets were rebuilt as the 660 Class they were made compatible electrically with the 620 and 900 Classes and could then work in multiple with them.

600 controls
600 Class Control Panel
Photo: Bruce Agland
 
The driver's controls are (left to right) direction and transmission control, master control key, throttle, horn and SEM brake valve.

620 controls
620/660 Class Control Panel
Photo: Bruce Agland
 
The driver's controls are (left to right) direction control (and master control key), combined transmission and throttle control, horn, SEM brake valve and three-position changeover cock.

620, 660, 900 AND 1100 CLASS RAIL MOTORS

The multiple unit system in these classes provides electro-pneumatic control of the throttle, direction and transmission. The throttle and transmission engagement control are combined, and the transmission "lockup" is managed automatically by a Woodward Governor depending on the road speed of the vehicle. The throttle control lever has five positions and they are selected by moving the control lever through five distinct "notches". The five positions are:

  • Neutral Idle - transmission disengaged and engine at idle
  • Transmission Idle - transmission engaged and engine at idle
  • 1/3 Revs - transmission engaged and engine at 1/3 revs
  • 2/3 Revs - transmission engaged and engine at 2/3 revs
  • Full Revs - transmission engaged and engine at full revs

Engine control is managed by solenoids providing the three fixed engine speed settings. As these are controlled directly by a "train wire", no EP feature (as used in the 600 Class) is required.

1200 CLASS RAIL MOTORS

The 1200 Class control system operated in a similar manner to the 1100 Class, except that the throttle position also governed the "lockup" speed of the transmission. The throttle air pressure also flowed into the transmission governor control piston. The throttle notches and transition speeds are:

  • Neutral Idle - transmission couplings empty and engine at idle
  • Transmission Idle - transmission converter filled with fluid and engine at idle
  • 1st Notch - engine at 1/3 revs and transition at 63 kmph (39 mph)
  • 2nd Notch - engine at 2/3 revs and transition at 74 kmph (46 mph)
  • 3rd Notch - engine at full revs and transition at 86 kmph (54 mph)

Although there was a difference in the engine speed control, the five positions corresponded with the identical positions on the 1100 Class controls and this enabled both classes to work in multiple.

THE EXPRESS PASSENGER TRAIN

The Express Passenger Train (XPT) control system is essentially similar to that used on diesel-electric locomotives. As the XPT operates in a "push-pull" configuration, the multiple unit controls are carried through all passenger cars. In general use, the trailing power car provides power for the electrical services throughout the train as well as power for traction.

ENDEAVOUR, XPLORER AND HUNTER CLASSES

The Endeavour, Xplorer and Hunter Class control systems permit the operation of trains of up to eight cars in length. The control system is computerised and provides comprehensive train information and in the Hunters is also integrated with the video surveillance cameras throughout the train. These cars have a combined throttle and brake controller with only the direction control being controlled separately. The outer ends of these vehicles (the driver's cab end) are fitted with multi-function couplers that permit one-person coupling and coupling. These couplers provide not only the mechanical coupling of the units but also connect both the pneumatic and electrical control connections between sets.

The Xplorer and Endeavour classes are fitted with Scharfenberg multi-function couplers, while the Hunter Class are fitted with Dellner multi-function couplers. These two coupler types may be used interoperably, however, the exchange of detailed train information data is limited. There are no conventional jumper cables deployed between the sets. However, the non-driving ends are fitted with Scharfenberg or Dellner bar couplers. Jumper cables are used between cars with the bar couplers, however, these are not generally required to be connected or disconnected while the units are in service.

Hunter controls
Hunter Class Control Panel
Photo: Bruce Agland
 
The driver's controls are (left to right) direction control, combined brake and throttle control, horn and vigilance control.