TOPS codes (wagon): MCO vs MHO

[t.s.meese]

I've puzzled over this for several months now. MCO and MCV are the typical TOPS codes for 16 ton mineral wagons, unfitted and fitted respectively; MDO and MDV for 21 ton minerals, and so forth. But what is MHO? M = Mineral; O = unfitted. H = some detail, I don't know! They appear (plentifully) on the Fox 16t transfer sheets , but I can find no reference to them on Paul Bartlett's site, or on any (detailed) TOPS lists I can find. My only thought/guess was that maybe the H is for rebodied wagons, but I've found what I think are rebodied examples with the middle letter C, so perhaps not, or maybe that was a later tweak? Or did they run out of suitable running numbers for MCO, so the H is an overflow character? Dunno. Any help appreciated.
Cheers
Tim.

[keefer]

LTSV has a list of wagon codes including MHA starting in 1993 but no mention of MHO:

https://www.ltsv.com/w_ref_codes_tops_m.php

[Rivercider]

1 hour ago, keefer said:

LTSV has a list of wagon codes including MHA starting in 1993 but no mention of MHO:

https://www.ltsv.com/w_ref_codes_tops_m.php

I have a TOPS Code Guide booklet dated 1978, which does not mention wagon type MH either

 

cheers

[HGR]

Not aware of any use of the code MH before the MHA box body conversions in the '90s as mentioned by 'keefer'.

 

However, bear in mind that MCO wagons transferred to the DCE fleet as general material carriers were coded ZHO.

 

[markw]

Isn't it the code for a 16t mineral with bottom doors (H for hopper-ish), can't think there would be many left though.

[t.s.meese]

2 hours ago, keefer said:

LTSV has a list of wagon codes including MHA starting in 1993 but no mention of MHO:

https://www.ltsv.com/w_ref_codes_tops_m.php

Yes - this is my primary source - but no MHO...

[t.s.meese]

1 hour ago, HGR said:

Not aware of any use of the code MH before the MHA box body conversions in the '90s as mentioned by 'keefer'.

 

However, bear in mind that MCO wagons transferred to the DCE fleet as general material carriers were coded ZHO.

 

Yes - I had noticed that. So perhaps the Fox Transfers MHO is a mongrel offering of MCO meets ZHO. Hmm...

[t.s.meese]

1 hour ago, markw said:

Isn't it the code for a 16t mineral with bottom doors (H for hopper-ish), can't think there would be many left though.

Ah - interesting thought. But on the Fox sheet there are none of the \/ symbols (white on black) to indicate bottom doors. Was that marking removed at the time of TOPS?

Edited March 1, 2022 by t.s.meese
improve clarity

[HGR]

55 minutes ago, markw said:

Isn't it the code for a 16t mineral with bottom doors (H for hopper-ish), can't think there would be many left though.

The bottom door variant were included in with MCO. The AARKND (the four-character TOPS code - see diagrams on Barrowmore web-site, etc) differentiated between the ones with side and end door only as MCO C and those with '... and bottom doors' were originally assigned MCO F but this was quickly changed to MCO D. Interestingly the MCO F variant originally was listed following on from the vac braked MCV variants, but maybe then realised that the bottom doors would preclude vac brake so was changed to MCO D as the next available MCO variant but remained at the end of the list. The bottom doors required the use of double brakes, without a cross-shaft, in order to leave the space under the bottom doors unobstructed. 

 

[Covkid]

I was under the impression that the large number of 16 tonners reallocated for departmental use were fitted wagons so became ZHV.

 

To muddy the waters a little, not all vacuumbrake fitted 16 ton minerals were coded MCV though. Some subdesigns had double brake cylinders rather than a single, so were (I think) recoded to MXV, in the early 1980s I think. My hazy memory says this might have been a decade after the introduction of TOPS, so maybe the "double vac cylindered" MCVs were recoded as MXVs.  Perhaps "Rivercider" can remember   

[Mark Saunders]

Clasp brake retained MCV code and those with push brakes became MXV!

 

The reason that was Google docks could not accommodate clasp brake wagons for discharge , possibly others too.

[Fat Controller]

Just a thought; I wonder if 'MH*' had been intended for the collection of OHVs that had been modified for shingle traffic from Lydd? These had the doors fixed shut, so wouldn't have been much use for merchandise traffic.