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Place your pointer over the 'buttons' below to show the different caption labels.
| No labels | Instruments & controls 1 |
Instruments & controls 2 |
Indicators & isolation switches |
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The selector has 4 positions OFF, AUXILIARY, FORWARD and REVERSE. In 'auxiliary' battery power is made available for him to lift the pantograph and start the MA sets or DA sets; he can also test the brakes in this position. He cannot demand traction until he selects FORWARD or REVERSE and has inserted his master key to unlock.
The power demand lever has 9 positions, OFF, notches 1-7 and BOOST, the traction power increases incrementally as the handle is notched up.
Boost enables the driver to obtain extra power for about 3 seconds in every 20 sec. to overcome difficult hill starting etc. The boost notch is spring loaded to prevent a continuous demand signal.
The brake demand lever has 9 positions like the power lever but works in the opposite direction. The levers are so arranged that if they are both pushed forwards - a natural motion for an emergency - the power is cut off and the brakes are switched to give maximum braking effort.
The power demand signal is removed should the brake lever be moved higher than notch 2. This enables hill starts brake application to prevent "slipping back" but prevents power and brakes being applied together unnecessarily. The last notch "EMERGENCY", like the power demand lever is spring loaded to prevent accidental application.
In addition to this normal brake demand lever there is an Emergency Brake Push Button situated in front of the normal control.
The system comprises 4 parking brake packs situated one in each van trailer and power car. Each pack can be operated individually, locally, or as a system from the driving cab. The selector must be in Forward or Reverse position before control can be taken. This is to prevent accidental parking brake release causing a train running away on a slope without braking effort being instantly available from the running brakes. The cab operating controls consist of 2 buttons APPLY and RELEASE and an indicator which shows ON, OFF or a cross-hatch meaning partial application.
On the floor in front of the driver is a foot-pedal which must be depressed whilst the selector is in the 'forward' or 'reverse' positions. Should the pedal be released for longer than a few seconds an emergency brake application is made automatically.
Should the system fail, it can be isolated by a switch behind the driver's desk front cover.
In principle the AWS for APT-P is the same as that used on current locomotives.
Should the system fail it can be isolated by a switch mounted to the right hand side of the front desk.
APT-P has not got an air train pipe; it has an electrical equivalent. In the leading driving cab there is a brake encoder unit (behind front desk). This takes the signals generated by the position of the brake lever and produces voltages to pass down the train lines to control the local electronic brake units. It also provides a sinusoidal current which is passed down a train line to the end of the train and returns through each electronic brake unit to the brake encoder unit.
If this current fails to be detected at the local electronic brake units it produces an emergency brake application. So, in general terms it operates exactly the same as an air train pipe, should the train break in half both portions would stop. In the driving cab the emergency brake loop is also open circuited - providing emergency braking through the actions of:-
This is a train wire passing along the train through lever operated switches in the coaches. This system replaces the Passenger Communication Chain in existing stock. If any passenger "pulls the cord" the electrical circuit is broken and the EBL is open circuited causing full emergency brakes. The driver can however push and hold a button on the driver's desk which overrides the brakes until he releases his thumb. This overriding can be done only on the passenger communication system and not on any of the other systems which can cause emergency braking.
Under the driver's desk is situated a "towing enable" switch which needs to be operated by the driver to energise the towing circuitry.
The purpose of the towing interface is to enable joint braking when APT-P is being assisted by a locomotive. Firstly, the towing interface is to provide emergency braking on both APT-P and the locomotive, which can be operated from either in any of the normal ways - broken train, passenger communication etc. Secondly, it enables a locomotive driver to have full linear control of APT's brakes, in addition to his own trains brakes, from his automatic brake handle.
APT-P can be considered as two half trains or rakes, each identical. Each rake has a motor alternator set (MA) situated in the van trailers and a diesel alternator set (DA) in the driving trailer cars which produce a 3-phase 415V 50Hz supply.
The MA sets have the greater outputs of 430kVA, compared with the DA's 250kVA, and are used as the main source of train power. Should a MA set fail the back up DA can be switched in with subsequent shedding of some load.
There is a small control panel at the driver's left hand side for control of the MA-DA sets.
It consists of an on and off switch with indicator for each MA set Local/Remote and for each DA set Local/Remote (4 on's and 4 off's),
Driver/Guard units are fitted in Driving cabs, Guards compartments and at each end of the Power Cars. They can be used as soon as the battery isolating switches are closed. The unit consists of a rectangular box with a standard GPO telephone handset fitted on the fascia, a call button and an electronic horn.
Each vehicle other than the power cars has a public address amplifier which drives up to 10 loudspeakers. In each Catering vehicle and Guards compartment a microphone unit is fitted which provides the whole train with Guard's comments and calls for meals and refreshments.
APT-P has 2 air horns which are situated in the nose cone. The pitches are different from other locomotives, however, being E♭ and C♭. Each horn has 2 valves one to produce full volume and the other to provide a softer sound. The loud valves are inhibited until 'forward' or 'reverse' is selected to limit the chance of maximum volume being applied in a depot or station.
In front of the driver are gauges which display:-
Early APT-P mock-up cab desk as seen in APT8.1 Technical Training Note.
Cab desk photographs by Colin J Marsden.
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