Steam and gravity sanding on Gresley locos

Hi all,

For the last couple of weeks or so, I've been trying to find out some of the more technical aspects of the K4, of which I am part of a team building a virtual model. Looking at historical photos, I can see that the sanding equipment seemed to alter on different locos at different stages of their lives - in the case of the K4s, forwards gravity sanders for the front pair of driving wheels, forwards steam sanders for the intermediate pair, and none for the reverse. I've seen one or two photos with the steam sanders missing, and I understand that 61994 has been modified with a set of all steam sanders for forwards and reverse, operated by an LMS directional sanding valve.

For the gravity sanders on Gresley locos, my understanding is that the driver will rock the long sanding lever open and closed continuously during operation. Is this strictly necessary to operate the gravity sanding gear, or is this a method of regulating the flow of sand out of the sanding pipe? Also, for those locos that have reverse gravity sanders, how does the driver discriminate between the forward and reverse sanders? Or does the movement of the handle simply release sand from both the forwards and reverse sanders simultaneously, and thus waste sand where it is not required?

Until fairly recently, I wasn't aware that A4s, K4s and some other Gresley locos were fitted with steam sanders when built, as I don't think I've ever seen or read about them in operation, either in person or on film. I've been fortunate to have had a day's ride out on 60007 a few years back, but I don't remember seeing a control valve for the steam sander, and looking at the plethora of footplate photos on the internet from the Great Gathering, I can't see one in those either! To be honest, I don't really know what I'm looking for, having never seen an LNER steam sander valve before as far as I'm aware, but none of the valves in memory or in the photos suggests that it operates a steam sander to me. However, it must be in there somewhere, and for the A4s I have a feeling it's hidden near the floor in the driver's "footwell" between the cab side sheet and reverser pedestal. Would anyone happen to know where it is and how it was operated in comparison to the LMS and BR steam sander valves? I could perhaps then guess where the valve would have been on a K4, or if not, see if the NRM have a K4 cab arrangement drawing.

I have another query involving the injector water feeds on 3500 gal group standard tenders, but I'll leave that for another thread and see where I get with this one first.

Kind regards, and many thanks in advance,
Chris

 

I'm not fully aware of the history of the sands on Gresley locos but I believe that he was impressed by the gravity sands on GWR locos so fitted them additionally. The trouble with gravity sands is that they are difficult to regulate, hence the constant open/close technique,, not just with Gresley locos but more or less universal. They would be much better if you coulf guarantee a controlled trickle of sand but that is asking a lot. Steam sanding should only put a minimum of sand down and can be better in windy conditions but, on occasions, may not put enough down to guarantee adhesion. You can generally leave steam sands on for a longer time without emptying the boxes because they use less. You can soon empty a gravity sandbox if you aren't careful. Too much sand can also add to the drag of the train.
The steam sand valvr on the A4's is a simple screw valve situated at about knee height to the right of the driver when in his seat. and in easy reach of him. The steam sanding valve on 61994 is an LMS/BR style one and has three positions. Moved to the left, gives sand to the front and moved to the right gives sand to the rear. Mid position is off.

 

That's brilliant, thanks Steve! I'm guessing that when Darlington built the K4s, they would have also had a screw valve to operate the one pair of forwards steam sanders, and if they had also had reverse sanders, they would use a fitting similar to that on 61264 and 62005, which looks similar to the LMS/BR fitting? I may have answered my own question about how the gravity sanding handle can operate the forwards and reverse sanders independently - looking again at 60007 I notice that it doesn't actually have reverse sanders. And looking at Great Western types that do, it appears there are actually two independent levers on a single base, for operating the forwards and reverse sanders, so I'm guessing the LNER types would have had similar setup. No doubt the N2 would hold the answer, but I've not had any luck finding cab photos to confirm.

Many thanks for your help!
Chris

 

I slightly mis-interpreted you query about forward/reverse sanding. I thought that you were referring to 61994 with its additional reverse steam sand. Most locos with forward reverse gravity sand have separate control handles but, it is not impossible to do it with one handle. For example, Sentinel locos (as in LNER Y1 & Y3) have one handle; you push it forward for forward sand and pull it back for reverse sand. Off when in mid position.