D78 AND 73TS CONTROLS
The D78 and 73TS stocks have some controls that appear different but perform the same functions. The main controls are the Selector and the "Combined Traction and Brake Controller" referred to as the CTBC. The following sections describe their purpose and how they operate.
Selector
The selector might be called a Reverser on other types of stocks, but on LUL stocks it performs more than just selecting a direction. It is a rotary control that has multiple selectable notches labeled SHUTDOWN, FOR2, FOR1, INTER, REVERSE. The D78 and 73TS selectors look similar and have the same labeled notches.
On entering the cab at the start of a scenario, the cab will be shut down and needs opening and various controls and systems enabled before entering service. The selector will be in the SHUTDOWN notch, verified by the TMS and Aux2 panel "Other Cab On" lights being lit. Enter the keystroke to open the cab (ctl shf S) and the Selector will move to the FOR2 notch and the "Other Cab On" lights will extinguish.
Note that we used the "ctl shf S" (S = Selector) key combination to distinguish it from the usual train direction controls (W/S) as the control performs the function of opening up the train, not just selecting forward direction. Subsequent movements of the selector into other notches are performed using W and S keystrokes, but these are seldom needed.
The FOR2 notch means the train will be able to provide full acceleration in the Forward direction. Under poor traction conditions, like leaf season with slippery running rails, you can move the Selector (W and S keys) to the FOR1 notch, which will result in 70% power and less chance of wheelslip. The stocks both include an anti-slip traction system, which *should* prevent wheelslip in most conditions, however the FOR1 notch is an additional aid if needed. The INTER notch is akin to "neutral" - no motoring, and is seldom used. The REV (reverse) notch is NEVER used during normal operations as the Operator would be unable to see the actions at the rear of the train -- the only permitted way to reverse the train in service is to change ends. It is only used by Depot shunting staff under very carefully controlled conditions.
Important:
Opening up the cab (Selector moved from SHUTDOWN to FOR2) brings multiple train systems into use and allows motoring of the train, and informs the train systems that "this cab" is the one controlling the train. It is, however, VERY IMPORTANT that the cab be shutdown (ctl shf S) to move the Selector to the SHUTDOWN notch before changing ends and opening up the other end cab. Failure to do so will trigger the Runback Protection System in the cab that is left open and unoccupied. (This system, its purpose and use will be discussed in a later post). So before changing ends, verify the Selector is in the SHUTDOWN notch and the "Other Cab On" lights are lit.
CTBC
The CTBC is a lever that provides control of both the train motoring and braking using a single control, and is moved in the simulated cab by the A and D key commands. In the D78 it is a lever with a red knob that moves fore/aft and is controlled by the right hand. In the 73TS it is a rotary lever controlled by the left hand. The levers in both trains have the same notch positions controlling motoring, coasting and braking as follows:
The D78 and 73TS use a 7-step Westcode brake system, but only employing notches 3-7. The 5 brake notches on the CTBC are labeled Brake1...Brake4 and Emergency. On entering the cab, the CTBC will be in the Brake1 notch - used to hold the train at a stand under most conditions. The other notches provide successively increased degrees of braking. There is also a notch labeled "Off and Release", meaning no motoring and no braking, and use of this notch during travel implies letting the train coast at the current speed. Note that entering the Off/Release notch on our VDL stocks will cause a deeper "clunk" noise that is distinctive compared to the other notches so you have a better sense of CTBC position. Likewise, the Brake4 notch is distinctive, alerting you that the next brake notch is Emergency.
There are 3 motoring notches, labeled SHUNT, SERIES, PARALLEL - each providing successively higher acceleration and max speed. Each has a distinct purpose:
Shunt is used for slow travel in restricted areas like depots and will slowly accelerate the train to a max of 10mph. The motors are connected in series with an additional ballast resistance to limit acceleration and speed.
Series is used for faster acceleration up to a max of 20mph. The motors are connected in series with gradually reducing resistance being applied as the train accelerates via the RPA (Rotary Pneumatic Actuator) system which is the cause of periodic "ticking" sounds heard on these stocks. (Note that we have included a realistic simulation of the RPA in the traction and rheostatic braking systems, and you will hear the RPS operating in the cab - listen for the ticking sounds during acceleration, re-motoring and braking).
Parallel is used for maximum acceleration up to a max speed controlled by the Coasting Control and Weak Field system, discussed elsewhere.
Typical CTBC operation:
Minimizing dwell time (time spent in a platform) is a way to enable frequent service with short headway between trains, as is required by an urban transit system like LUL. This is achieved by using efficient braking and rapid acceleration to bring a train into and out of a station efficiently.
Under normal conditions, accelerate from rest using the Parallel CTBC notch. The train will accelerate quickly, reaching about 28mph by the 6-car count-up board on level track. Continue accelerating until either the Coast Control cuts in at 31mph, or (if WF or Coast flags are raised) you reach the permitted line speed, or appropriate speed for conditions.
When braking approaching a reduction in speed limit, Brake1 or Brake2 will typically be used, ensuring that speed is reduced before passing the limit board. Note that the Off/Release notch - enabling coasting at current speed, subject to gradient - can be very useful. The train is not always accelerating or braking, but very often needs to coast (maintain approximate current speed subject to gradients).
Braking into a platform, unless entering a dead-end termini with controlled speed restrictions, is usually performed passing the platform end at 30mph and then selecting Brake2 (maybe Brake3 for shorter platforms), and reducing to Brake1 about 2 cars in, and juggling Off/Brake1/Brake2 a little on approaching the stop mark (diamond plate on the sleeper, with a platform monitor in view through a cab window). With practice you will get more efficient. On roads with higher speeds - e.g. approaching Kew Gdns WB at 40mph, select Brake3 at a position 2 cars out from the platform, then reduce to Brake2, Brake1, etc. as needed to bring the train smoothly to a stand at the mark. Faster approaches take more practice.
Folks without LUL training tend to think that applying light braking and increasing if needed might be the right approach, whereas the opposite is true. You should always apply the maximum braking needed (e.g Brake 2 or Brake3, or even Brake4 in extreme situations) from the beginning of the braking process -- this gets the train under control. Then gradually reduce braking as you approach the stop mark. A skilled operator will notch to Off/Release just as the train rolls to a gentle stop and then apply Brake1 to hold it in place, and thus minimize jerking the passengers around -- yes, there's simulated paying public behind your cab rear wall :-)
A note regarding the Rheostatic braking system
The D78 (and 73TS) use a blend of Westcode air-operated and Rheostatic electric braking on all motored cars (DM and UNDM). The Rheo portion of this uses the train motors and a resistor bank applied by the Rheo RPA system to provide additional braking, with the amount of Rheo braking (resistance level) being speed-dependent. The Rheo system becomes active at its maximum level at about 40mph, gradually reducing the Rheo brake level as speed decreases, and finally dropping out at about 12mph.
One thing to note, is if you move the CTBC out of a brake notch and into Off during deceleration and them re-apply, the Westcode and Rheo brakes will continue to blend at speeds down to 20mph. However, if you re-apply brakes at or below 20mph the Rheo portion will not re-apply and you will have less braking force than you might expect (only Westcode active on all 6 cars). If you are not alert that this will happen, you might over-run your stop point due to insufficient braking.
If possible, do not release the brakes fully (i.e.maintain at least Brake1) decelerating below 20mph in order to maintain consistent braking; and if you are unable, be aware that brake force for a given CTBC brake notch will be reduced below 20mph and allow for this as part of your braking procedure.