Hattons Class 66 .... Then there were Six!

As more units have joined the fleet, I've made a few adjustments and updated the earlier locomotives to a similar standard where appropriate. I'll use this webpage to summarise the current configuration and decoder settings.


The Hatton's 66 Fleet


Mechanical Mods:

All the locomotives suffered from varying degrees of "The Hattons 66 wobble" due to the rotating axle end pieces interacting with the bogie sideframes. It was a brave design choice, but  not the end of the world to forego and I wasn't so impressed with the lateral movement of the end caps as the locomotive negotiated curves. So my fix is the simple option of removal, cut off most of the shaft & superglue the end caps over the resultant holes in the bogie sideframes. No more wobble and no need to keep an indefinite lookout for detached axle end pieces.

If you your eye sight is good enough to really want to retain the rotating wheel bearing covers.... Take a look at Peter Dixon's YouTube channel, which includes tutorials identifying the essential steps needed to correct misalignment of the bogie side frames and the outer wheelset axles on each bogie. Also his technique to slightly increase the diameter of the bogie side frame holes to improve the axle end piece clearances.

Modified bogie with truncated end caps glued in place.


The Decoder and Sound System:

The LokSound V5 MKL with Legomanbiffo sound software plus big EM2 speaker worked so well in my first Hattons 66, I've used the same solution in all the others.

Just need to remove the motor parallel capacitor and over voltage protection device to allow the decoder to seat correctly.

Motor Over voltage protection device preventing the decoder seating properly. This and the adjacent capacitor were subsequently removed.


DCC motor characteristics:

The 5 pole motor and twin flywheels combine with the heavy chassis weight, to deliver smooth powerful performance over the entire speed range, except for the minimum speed step, where some hesitation is apparent. (I think this is due to the static magnetic properties of the motor.) Adjustment of the low speed BEMF control CVs minimises this effect and renders it largely unnoticeable in normal operation. The remaining motor control CV settings are non critical.

The ESU "Exponential 1" speed characteristic is applied via the LokProgrammer. The remaining motor control CV settings are tabulated below.

Braking Changes:

 Bif's standard set-up involves the use of long acceleration and deceleration periods to simulate the momentum of heavy trains. This is supported by a brake key which reduces the deceleration time when needed.

I have adjusted the brake CV from Bif's reduction in stopping time of 50% to a reduction of 80%, in order to provide somewhat speedier braking (CV179 to 204) . I have also modified the function mapping to make key 5 work as the brake key on all 3 function key ranges. (i.e. F5, F15 and F25) This facilitates immediate braking regardless of the selected controller function key range in use.


Train loading simulation:

I've also used the LokSound V5 variable load options to add a light engine operating mode with lower simulated momentum shorter acceleration and deceleration times ("Optional Load" CV103 to 63) and a maximum load train mode which extends the acceleration and deceleration time to simulate very high momentum train operation ("Primary Load" CV104 to 255).



Lighting Control:

I have now changed the lighting control on all the 66s from Bif's original concept, to instead provide independent lighting control at each end of the locomotives. I found this simplified consist operation of the two DRS 66s I use on military nuclear flask trains etc. It then made sense to apply the same modifications to the other Hattons 66s, to maintain a common approach.

Key F0 activates directional lighting at the driver's end. Key F20 does the same at the other end. Key F22 changes headlights from day to night (except for the DB loco, where it switches headlights from main beam to dipped.) Key F23 disables headlights for in-yard work.

With other lighting keys off, Key F21 activates parking rears at each end and Key F24 alternately flashes marker and rear lights at both ends as warning lights when shunting.

Key F19 activates the forward cab light in the direction of travel but only when the locomotive is stationary.


The LokSound V5 MKL has enough full power function outputs to drive rears, markers, day & night headlights and cab lights independently at both ends of the locomotive. This means that variations on Biff's original lighting control theme can be largely achieved using a LokProgrammer to change the function mapping.

Table indicates the LokSound V5 MKL decoder function outputs used for each lighting function


Function Mapping update for the Lighting:

GBRF, Freightliner and DRS locos are driven with the short cab / roof fan vent end forward.

The lighting sections of the function mapping for these locomotives are reproduced below as they appear on the LokProgrammer screen.

Colas and DB Schenker locos are driven with the long cab / roof exhaust end forward. Mapping for these locos is as follows:

(The direction control of these two locos is reversed via CV21.)

Cab lights, parking lights and super-shunter lights are common to all locos. Mapping of these is as follows:

(The mode [2] front and rear plus Aux1 and Aux2 light configuration outputs flash alternate markers and rear lights.)


Dimming the upper marker lights:

As received, the upper marker lights are typically brighter than the headlights on all the Hattons 66s. To reduce the intensity of these lights, an additional series resistor (value circa 39k) has been added at both ends of the locomotive.

Hatton's 66 variants with large headlights:

e.g. My Freightliner and Colas 66s.....  An unfortunate design error resulted in only a single lower marker light coming on at any time, together with the headlight on the opposite side. Fixes for this issue are described in some detail in another of my web pages. (See site menu).

Large headlight Freightliner 66.


My DB Schenker 66 has modified headlights with corresponding changes to the markers, to simulate the new all LED Wipac lighting modules on some DB locomotives. These mods are described in detail on another dedicated web page (see site menu).

DB Schenker 66 with modified headlights.


Re-arranging the Function List:

Bif's original function list has been adjusted to incorporate the changes described above. The revised list is as follows:

The first member of the fleet, a GBRF 66.

Adding a Stay-Alive Circuit:

For added reliability, on all locos, I've added an AVX 6800uF 15Volt supercap, sourced from YouChoos, with a simple zener diode protection circuit to prevent excessive charging voltages.

The stay alive circuit is bonded to a plasticard substrate which is in turn glued to the chassis block. 

Simple stay alive protection circuit


The two DRS 66s working in consist.


The Hatton's Class 66 model is not without its problems. The good news is that most of the issues can be fixed with a little effort. Once this has been done, the result is a superb model. When combined with Legomanbiffo's sound software, on board an ESU LokSound V5 MKL, driving an EM2 speaker, the result is, in my opinion, by far the best 1/76 scale Class 66 sound equipped model currently available. The powerful motor and heavy chassis, provide really impressive pulling power.


The Colas member of the fleet (this also has corrected configuration large headlights ).

Supplier website links:
Hattons    The Class 66s were all designed and sourced from Hattons.
YouChoos    Source for Stay alive super capacitor.
Digitrains    Source for blank ESU LokSound V5 MKL decoder (Sound software sourced separately from Legomanbiffo).
Roads & Rails    Source for EM2 speaker
DCC Concepts    Source for sub-miniature pre-wired Nano-LEDs



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