Peter Nutbrown: Radio control and bogie rebuild: Accucraft 3 cylinder Shay

fthe cab with the gas tank removed showing the
whistle valve, throttle servo and cables fed into the rear bunker.

No. 5 Mich. Cal. Shay

Purchased second hand through Simon Whenmouth June 2021, the loco is by Accucraft, possibly second generation and the condition was clean. Remedial work by Simon included resetting the gears, and a steam test on a rolling road. Being manual the loco was initially run on all circuits to check for clearance and the minimum radius of operation and the feasibility of it being converted to R/C.

The running test proved that the setting of the geartrains was still somewhat out, and the loco ran fine around the 60” radius circle but failed to negotiate the reverse curves or the tunnel curve. Pressure was maintained at 40 PSI, 15 PSI below the maximum recommended pressure. The speed was ideal though slower in the forward direction as is often the case for Accucraft locos due to the bobbin style reversing valve.

It was noted from the operating handbook acquired from the internet that the boiler is to be filled to half a glass and topped up during service, no doubt due to there being no superheater to dry the steam and reduce the opportunity for hydraulic locking of the engine due to carry-over. The benefit of this is a noticeable plume of steam vapour even on warm days from the funnel at all pressures.

The loco was stripped down and fully cleaned, showing clearly the painting that had been done on the running boards, cab area and exposed brass nuts and screws. Matt black was applied to complete the remaining bare sections of boiler and fittings within the cab and a brown/black mix was used to repaint the running boards which had originally a maroon tint to the brown, though better than the original black. This mix of colours was used to overpaint the red which had been applied to the buffer beams transforming the general look of the loco.

A new pin was machined for the multi height coupling.

An Enots style water filler valve had been fitted to the steam turret. Therefore the oversized water pump was removed from the rear bunker because it was redundant. This left ample room for fitting the reversing servo, 6v. battery pack and the Flysky FSI-6B receiver which indicates the voltage on the transmitter screen. Two holes were drilled in the bunker for the reversing arm and the rear lamp power supply. The existing hole for the feed water pipe to the boiler was utilised for the two servo and lamp cables.

The non-return water inlet valve was removed from the boiler back head and the 5mm connection utilized for a whistle valve. A Regner whistle valve and connector were fitted to the back head and a hole drilled in the footplate for an operating rod. The servo was mounted below the footplate behind the simulated firebox. The pipe to the whistle was fed behind the engine along the RHS running board.

Rear bunker showing the electrics above the reversing servo.

General view of the cab with the gas tank removed showing the
whistle valve, throttle servo and cables fed into the rear bunker.

A red LED was placed in this hollow firebox to indicate a fire.The rear lamp body was found to be loose on its mounting bracket and was removed in an attempt to replace the concave inner shaped part. The centre plug simulating a lamp was pressed out and the hole enlarged so that a 5mm white diode could be fitted instead. A 5mm hole was drilled in the rear of the tender to feed the wires through to a connector. Similar actions were taken to the front lamp where the wires were fed through a painted brass tube on the RHS running board to the cab. These cables were connected to an unused channel on the receiver so are permanently lit when the receiver is switched on.

On the test run for the radio control on the portable layout the loco frequently derailed on the 40” radius curves and stalled occasionally.

The bogies were removed and after some stripping down major problems were found.

Bogies cleaned up and debris removed

The front bogie front wheel had no sideways play resulting in the gears becoming stiff at one position. This was due to the gear wheel not being mounted squarely on the driven wheel, being 0.6mm out of true, taking up all the available sideways play on the axle. Approximately 0.2mm was machined off the diameter of recess of the driven inner wheel boss which now allows the gear wheel to sit square when tightened up with the three screws onto the outer face of the driven wheel.

Gear wheel now mounted square on the driven wheel.

New spacers were made giving all the axles approximately 0.5mm of axial movement. When removing the wheels from the bogies, it was found that the upper central mounting box sections were both damaged, the vertical limiting lugs were either broken or missing with some of the debris stuck in the guide areas. On the rear truck the mounting box was jammed in the down position resulting in the top of the bogie frame rubbing on the tie bars for the firebox, removing paint and limiting the available movement. The front bogie was jammed in the up position by paint and debris on the tie screws. To sum up there was no flexibility between the bogies and the frame of the loco. 

An attempt was made to utilize the soft cast metal box sections by adding stainless vertical limiters to the sides but the parent material failed under the strong spring load on assembly. A solid 12.5mm square brass bar was fashioned to form two new mounting box sections using the 5 springs and 4 limiters for each, this resulted in free movement of the bogies in all directions without fouling the tie bars.

Bogie box centre section up after cleaning, this would allow the
bogie to slip off the box section as there are no limiting lugs at the

Bogie box centre section in the down position, swivel movement
restricted by the tie bars of the firebox.

New brass block made.


The drive pinions and bearing bushes were incorrectly set, the rear one in particular allowing the drive square to drop out even on 48” radius curves, whilst the front square bottomed on the driver tube restricting the movement of the bogie on LHS curves to less than 5 Degrees from dead centre. Using curves of varying radii the bearing bushes and pinion gears were reset achieving a minimum radius of 40” In order to achieve this 4mm was machined off the front bogie square drive shaft. It was found during adjustments that both the steel bogie drive shafts had indents drilled for two of the four axial movement limiting bearing bush locking grub screws and it was common sense to maintain this level of security and machine the square instead.

The loco was run on test and functioned well, maintain pulling power even at 20 PSI for the considerable load of 12 bogie wagons. As the loco warmed up and began its run it was noted that steam vapour was present around the cylinders, this was followed by copious amounts of cylinder oil, lubricating the cranks and bearings thoroughly. It was noted that no oil passed out of the funnel and the burner was quieter than normal for an Accucraft loco, possibly due to the clutter in the cab.

Now where do I fit a driver and fireman?

August 2021
































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