Google ‘electric train staff’ for the basic details of the train-staff system.
The idea is to have a mechanical piece that confers route authority on its possessor, perhaps by insertion into a device that then works with some version of automatic train control.
If a train is moving quickly, you have some of the same problems as in relay races, with the physical staff ‘slapping’ into the fireman’s (or whoever’s) hand with what can be severe force. Therefore arrangements like those used for high-speed mail cranes can be used to let the staff be ‘picked up’ at any speed, retrieved from its catcher, and inserted or used appropriately. (There is at least one episode of the old TV show “Railway Roundabout” that specifically shows one of these in use…)
I suspect there may also be devices that automatically register the staff as well as exchange it – I’ll hand that to Mr. Clark to describe in detail.
The token, or staff is effectively a permanent “train order” between two locations. Variations in the system are described in the Wikipedia article. The name “staff” is used for the cylindrical version of the item used in the interlocked machines.
The electric staff system consists of two machines electrically interlocked, so that only one “staff” can be removed from either machine at a time. While there is an illustration in the article, the operation can be observed in this video:
This, at 16.00 in the video, shows a manual exchange, but an “automatic” or more correctly mechanical exchange is similar. The video shows the electric staff machines in use.
Clearly, it is better to describe the system on a locomotive that actually has the sys
Bolster offset is nearly a yard, over 1/5 of the overall truck wheelbase. Presumably this is to control coupler concerns with swing, and there is no issue with increased side ‘overhang’ on curves.
I presume that the thing at the extreme inboard top of the trucks is an ‘enhanced’ traction-motor blower duct. I’d be interested to see detail pictures and a description of what that feature does, as there’s nothing like it at the ‘leading’ end of the trucks.
Can someone explain the rationale for terming these “Trimounts”? They have equal axle spacing, presumably all the traction motors ‘face the same way’ in the frame, and they have no external drop equalization… I considered the offset bolster in a North American Trimount to be a matter of necessity, not choice.
I’ve always associated the term Trimount to indicate a truck with a pivot on or near the transom between motors 1 and 2 and a pair of secondary springs on the sideframe between axles 2 and 3, either with a fixed or sliding interface, resulting in 3 points of support with little secondary spring travel. I welcome any correction to that thinking.
That would make perfect sense if we assume it is a bearing pivot, which gives precisely the three-point support you indicate and would be a perfectly rational explanation for the name.
It also explains something about why the pivot would be spaced opposite and at equal distance from the two support pads, with the geometrical center of the truck in plan in the ‘center’ of the triangle, to make the best use of the three-point support so provided.
Firstly I should state that the drawing reproduced is a railway drawn diagram, not one from Clyde Engineering, and it is quite possible that the draftsman is just tracing the builder’s diagram without understanding any of the content. However, that’s what we have on line and it shows the main features, if a bit oddly.
AS pointed out by Overmod, the traction motor blower ducts show up with more prominence than they deserve, and all three are visible, the other two being partly concealed by the three suspension points.
The really sad part is that in this version of the drawing no body bolster is shown over the designated bogie pivot.
However, by comparing the “G class” drawing with the “N class” drawing, it can be seen that the bogie frame itself is very similar. The HT-C analog on the N class has a bolster with four point support on the bogie frame, each with a rubber/metal sandwich support pad.
On the “G class” the “bolster” is a simple plank with a central pivot carried on rubber pads. Thus the pivot is offset towards the locomotive headstock compared to the older design. The two body support springs completing the three trimount points are located where the bolster pads would have been on an HT-C.
It is possible that the same wooden moulds could be used for the casting for both the Trimount and HT-C analog versions with minor interchangeable sections of mould.
On the Alco Trimounts the two supports away from the pivot were locally called "ele
So the meaning of “staff” is from a “swords and sorcery” game or novel of a cylindrical object granting the the bearer status, power, authority or the ability to cast spells as opposed to the group of workers who have to answer a politician’s mail?
Could this granting of track authority be exchanged with some kind of electronic token, using encryption to make it secure?
No, nor is it a euphemism for bread or a phallic symbol or a representation of the critical part of a railroad watch.
The original system involved a piece of unfakable wood, possession of which (like the gavel at a meeting) conferred authority to occupy a piece of track – anyone else approaching the track wouldn’t have it, and therefore couldn’t proceed. There was nothing special about the baton shape except that it was easy to pass back and forth between a train and the ground. Other railroads utilized a ‘tablet’ system, which was kind of like a flat disk or purse-shaped object with a ring handle that could be put on a hook or, later, exchanged with mail-crane-like equipment. If I remember correctly, some of these were made with wards or other special enablement to unlock specialized signal equipment when inserted – so that no ‘other’ tablet could be used where access was to be restricted specifically. By inserting the staff into a ground-based device, for example, a counterpart staff could be released from its ccarefully-tamper-proofed counterpart device at the ‘other end’ of a block…
I don’t recall this being used extensively in American practice; we went to electronic communication of written or verbal orders instead of possession of a device.
It could, although I suspect simple passphrase-style protection would work better than encryption to any necessary level of security in what, after all, is a near walled-garden proprietary system even if ‘interworked’