The photo above, blown up from State Library of WA 1458B/25, is of 2 LB or Q class wagons on Bunbury Jetty around 1900. They are in their original grey livery carrying the sort of timber load that they were intended for.
In the earliest days of the WA.G.R. timber traffic was handled with I class single bolster wagons and N class Twin bolster wagons. From 1897 the first Lb class bogie bolster wagons built by Stableford and Co started to arrive. They were numbered 2064 and 4439-4501. In practice they were used for all manner of loads.
At left is a photo of Q4477 with an interesting load before about 1910 (note that the inner bolsters are outside the line of the queenposts).

Some, at least, of the Q's, initially had 3 bolsters rather than 4 and they may all have been built like this. The oldest (and crudest) WAGR outline diagram that I have for a Q shows three bolsters but the outline diagrams from 1903 don't record this variation. The photo below, blown up from State Library of WA photo 1458B/18, shows LB4460 and LB4455 (far right) in this condition in 1898 at Wokalup. In 1901/2 two wagons (4473 and 4494) had their bolsters replaced with a single central bolster and became boiler wagons. They were later to be reclassified QB. Alteration from 3 to 4 bolsters for the rest must have happened at around about the same time. A little mystery surrounds wagon 4897. In 1900 this wagon was listed as a U class along with a few other odd wagons in a series which appear to be ex contractor wagons. By 1909 it had been converted to class Q. At present I do not know its origins. With the completion of the Goldfields Water Supply pipeline many of the U class wagons were converted to class Q in 1904 - 1906 (which is probably when 4897 was also converted. They were as follows:

1904/5	689, 692, 693, 2977, 2978, 2979, 2981, 2984, 2988, 2994, 3201, 3204, 3205, 3209, 3210, 3212, 3215, 3218, 3223, 3224, 3228, 3242, 3243, 3248, 3523, 3526, 3528, 3529 converted from U
1906	690, 691, 2976, 2983, 2985, 2986, 2991, 2992, 2993, 2996, 2997, 2999, 3000, 3202, 3207, 3208, 3211, 3216, 3217, 3219, 3221, 3222, 3226, 3227, 3230, 3231, 3232, 3233, 3234, 3235, 3236, 3238, 3239, 3240, 3244, 3245, 3246, 3247, 3521, 3524, 3525, 3530 converted from U

Early diagrams show that the positioning of the bolsters was different on the converted U's compared to the original Q class wagons. On all of the wagons the outer bolsters were directly over the bogie centre lines. On the original wagons the two inner bolsters were further toward the ends of the wagon (and outside the line of the queenposts on the chassis) than on the converted U's (where the inner bolsters were between the queenposts). There were also another four bolsters without uprights either side of the bolsters over the bogies on the converted U's in the beginning but these seem to have been removed fairly early on if ever fitted. Q3243 below is a converted U. The two outlines diagrams are shown below that for comparison. In 1910 Q2983 was sold to Smith and Timms for use on the construction of the Port Hedland - Marble Bar line. A replacement was built at Midland Workshops in 1911, which took the number 2983. In 1912 when the Port Hedland line was completed the original 2983 was re-purchased from Smith and Timms and given the number 8823. It remained at Port Hedland. Whilst most of the J (later JA) class bogie water tankers reverted to class U when the tanks were removed, two of them (3200 and 3527) became Q class wagons (in 1922 and 1915 respectively). In 1929 two wagons (690 and 3227) were temporarily converted to carry oil tanks and reclassified QD. This did not last long as new, purpose built tank wagons were entering service at that time. In 1931 the two boiler wagons (4473 and 4494) were finally recognised as a separate class and reclassified QB. In 1932 one wagon (3234) was written off. This was presumably lost as the result of the accident at Indarra. Another ten (2993, 2996, 3201, 3204, 3223, 3248, 4439, 4452, 4461 and 4471) were "temporarily" fitted with pipe bolsters as were eight more (692, 2999, 3217, 3221, 4442, 4445, 4475 and 4500) in 1933 and a final seven (2979, 3244, 4463, 4470, 4472, 4481 and 4483) in 1934. I do not know how long this lasted but 2996 and 3204 are believed to have still had the pipe bolsters until 1942. Two wagons were sold in 1937 (3210 and 4462) and one (4475) was fitted with a van body for the conveyance of diesel engines - and at some point reclassified QD. However the main event of 1937 as far as this class was concerned was the conversion of a large group of wagons to class R. Despite their official title as "timber wagons" the Q's were used to carry large quantities of bagged wheat during the grain season and it is likely that this conversion programme was the result of the shift to bulk wheat handling which started in the early thirties. More followed in 1938 and 1939 as follows.

1937	691, 2064, 2984, 2985, 2986, 2993, 3202, 3215, 3219, 3230, 3231, 3232, 3233, 3235, 3239, 3242, 3244, 3245, 3246, 3248, 4446, 4448, 4454, 4459, 4466, 4468, 4469, 4470, 4485, 4491, 4495, 4496, 4499 converted to class R
1938	689, 692, 2976, 2977, 2978, 2979, 2991, 2992, 2997, 3205, 3207, 3208, 3216, 3218, 3236, 3238, 3243, 3521, 3524, 3528, 4442, 4443, 4445, 4447, 4449, 4451, 4452, 4453, 4457, 4458, 4460, 4461, 4463, 4467, 4471, 4476, 4481, 4483, 4486, 4489, 4490, 4492 converted to class R
1939	2999, 3000, 3221, 3228, 4444, 4450, 4455, 4493, 4498 converted to class R

Two wagons (693 and 2981) were converted back to class U in 1940 - presumably because of wartime traffic demands but otherwise this class was little affected by the war. In 1951 the lone Q class wagon at Port Hedland (8823) was sold to the PWD when the line was closed. The diagram above dates from the post second world war years and shows yet another position for the inner bolsters (directly over the queen posts). It may be that the existing wagons had been altered or hat this only applied to new conversions - I don't know). The arrival of the new RC class wagons in 1954 rendered many of the old R class wagons redundant. With useful life still left in their chassis many were converted to class Q in 1954/5. Some of these had been Q's which were converted to R's in the late thirties (3221, 4444, 4447, 4483, and 4489).

1954	1610, 1615, 1630, 1655, 1662, 1693, 1701, 1722, 1743, 1756, 1758, 1773, 1774, 1811, 2196, 2877, 2888, 2895, 2962, 3361, 3450, 3457, 3463, 3471, 3505, 3516, 3542, 3560, 3576, 3579, 3610, 3617, 3619, 3625, 4583, 4646, 4709, 4756, 4761, 4773, 4775, 4788, 4805, 4818, 4819, 4828, 4847, 4861, 4866, 4874 converted from class R
1955	1592, 1614, 1625, 1669, 1673, 1691, 1736, 1780, 1822, 2152, 2159, 2880, 2883, 2884, 2889, 2901, 3370, 3451, 3461, 3477, 3492, 3496, 3518, 3541, 3545, 3568, 3586, 3615, 3618, 3633, 3642, 4387, 4599, 4614, 4624, 4633, 4653, 4662, 4675, 4681, 4689, 4751, 4752, 4753, 4760, 4789, 4799 converted from class R

However, another conversion programme started to reduce the numbers in the class once again from the mid-fifties. In this conversion wagons were fitted with pipe bolsters and reclassified QP. This was not temporary and the wagons concerned did not return to class Q. On the face of it, it would seem to have been simpler just to have converted some wagons direct from class R to class QP. This conversion programme continued on an ad hoc basis until the late sixties as follows:

1955	2877, 2996, 3204, 3209, 3217, 3224, 3525, 3529, 4440, 4441, 4465, 4480, 4482, 4488, 4497, 4897 converted to class QP
1956	3212, 3247, 4472, 4477, 4478 converted to class QP
1962	1662, 1673, 1722, 2152, 3492, 3642, 4775, 4799, 4805 converted to class QP
1965	2983, 2994, 3211, 3221, 3223, 3226, 3227, 3526, 4662 converted to class QP
1967	690, 2988, 3527 converted to class QP
1968	4474 converted to class QP

A final boiler truck conversion (4709) took place in 1962 when 4709 became a QB. Another conversion programme started in the same year. This produced the QBB class wagon. In this conversion the underframe was strengthened with angle iron truss rods and six evenly spaced bolsters with much larger uprights fitted. The Q class wagons converted to class QBB were rebuilt as follows:

1962	1592, 2159 converted to QBB
1963	1625, 1736, 1758, 1780, 1811, 2880, 2889, 2901, 3450, 3461, 3496, 3542, 3586, 4447, 4483, 4583, 4599, 4624, 4751, 4818, 4828 converted to QBB
1964	1610, 1614, 1655, 1669, 1756, 2196, 2883, 3451, 3541, 3633, 4444, 4633, 4646, 4653, 4675, 4752, 4753, 4760, 4819, 4861 converted to QBB
1965	1630, 1691, 1693, 1773, 1774, 1822, 2962, 3361, 3370, 3477, 3516, 3545, 3560, 3568, 4387, 4689, 4756, 4773, 4847, 4874 converted to QBB
1966	2884, 2895, 3619, 3625, 4614, 4788, 4866 converted to QBB
1967	1615, 1701, 1743, 2888, 3471, 3505, 3518, 3576, 3579, 3610, 3615, 3617, 3618, 4681, 4761 converted to QBB

Relatively few Q class wagons were written off as such, most being converted for other uses or extensively rebuilt for the same use (e.g. the QBB conversion). The remaining wagons were written off as follows:

1963	3463, 4456, 4489, 4789 written off
1965	3457 written off
1967	3222 written off
1968	3240, 3530, 4484 written off 4479 to JETTY 358
1972	3201 written off
1973	3523, 4439, 4487 written off
1974	3200, 4464, 4500, 4501 written off

Three of the last four survivors were wagons originally built as Q's in 1897. I am uncertain if any Q's ever got the yellow livery.