Relined Clutch Plates
The clutch plates were sent to the company in Cumbernauld for relining. The new linings were riveted on just like the originals.
On return, the linings needed to be skimmed to fit between the steel plates either side that are pushed together to clamp the friction plate. Unfortunately the Ruston manual does not give any details of the correct thickness. However they do give details of a gauge to check that the plate spacing is even all round which suggested the gap should be between 0.810" and 0.840". The gap between the disks is not easy to measure once things are assembled, but the actual gap was less than this - there had obviously been subtle design changes since the manual was written.
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| Slow and Medium Clutches |
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| Relined Fast Gear Clutch in Place |
The clutch plates were carefully set up in a lathe and skimmed. By a bit of trial and error the optimum thickness was determined to be between 0.780" and 0.790". The process of skimming is also useful in minimising the effects of warping of the steel clutch disk - this can and does happen due to overheating when in use. This of course depends on the plate being set up in the lathe chuck to rotate about the same axis as in the gearbox.
Once the clutch assembly was back together the clutches could be turned by hand although some friction drag could be felt because the plates had been skimmed to leave maximum friction plate thickness. Hopefully the clutches will bed in once in use.
Meanwhile the gearbox casing had been cleaned and was ready to receive the refurbished clutch assembly. Fitting was the reverse of removal, again using the forklift to lift the assembly into the cab. After that it was manually lifted into position in the lower casing.
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| Fitting the Strap |
On the Forklift 
Manoeuvring into the Cab 
Clutches Back in Place 
Underside of the Top Cover
With new gaskets made the top cover was lowered into position and bolted up ready to be filled with oil and tested. The clutch adjustment springs for each gear were adjusted so that the "pull" required to engage each gear via the lever was the same, and not excessive.
Gearbox Dipstick
The Ruston gearbox is a slightly strange arrangement with separate compartments for the main gearbox and the transfer gearbox (which turns the axis of rotation 90 degrees and contains the forward and reverse dog clutches). The two compartments have different oil levels and are not connected, although oil does get through the bearing between them. On Queen Anne's gearbox there are no dipsticks but there is an equalising valve that lets excess oil drain from the main (upper) gearbox to the transfer (lower) gearbox. The lower gearbox has a tap on the side corresponding to the correct level of oil. To get the correct level, you must put too much oil in the main gearbox and then open the tap - when oil stops coming out, the level is correct!
To improve on this, it was decided to make a dipstick for the transfer gearbox. There is no way to place a dipstick on the gearbox casing that is easily accessible, so it was decided to use a Manometer arrangement to locate the dipstick somewhere more convenient. To avoid machining the gearbox casing (which would risk getting metal swarf inside) the drain plug was extended by a "Banjo Union" arrangement which permits a pipe to be fitted to connect with a separate tube for the dipstick. The oil levels in the gearbox and dipstick tube should then be identical. The following pictures explain how this arrangement works.
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| Banjo, Dipstick Tube and Dipstick |
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| Banjo, connecting pipe and Dipstick Tube |
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| The top of the Dipstick Tube |
As can be seen from the photographs, the gearbox dipstick is on the left-hand side of the engine and easily accessible via the bonnet door.
Initial Tests
Although Queen Anne had not run for nearly a year, and the battery had not been charged, it started first time. The loco was in the carriage storage shed between the crane and the LMS Officer's Saloon. There was enough space to run up and down between these two to test the clutches. It was noted that there was some residual drag in neutral which made the forward and reverse gearbox engage with a "clunk". This should improve as the friction plates bed down.
A few weeks later while the crane was out of the shed, Queen Anne was coupled to the Officer's Saloon and driven up and down the siding behind the signal box. All clutches behaved well and taking off in slow gear with the coach attached was effortless.
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| Firing up |
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| Back out in the open |
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| A successful test |
It is intended to do further tests with Queen Anne hauling various loads around the yard at Aviemore and up to the station and back. However this needs to be done out of season on a day when service trains are not running.
A video of these tests will be posted shortly.
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