Looking through the British Columbia Photo Archives I found an interesting Minimum Gauge tramway in the Queen Charlotte Islands (today known as the Haida Gwaii archipelago). The tramway was attached to the ore bunkers of the Ikeda Mine, supplied by a horse-drawn 36" gauge tramway.
The Queen Charlotte Islands are separated from mainland British Columbia by the extremely rough Queen Charlotte Sound and Hecate Strait. Even today barges are not recommended for transit to the archipelago and in the early 1900's barges were not used to transport ore across the straits. Small mines shipped their ore in sacks. Large mines needed a way to transfer their ore into the one or two bulk-loading holds of the local coastal passenger/freighters. The Ikeda Mine was the largest mine in the Queen Charlottes before World War I with a 1000 ton (or roughly 500 to 700 cubic yard) bunker.
The story of the 36" gauge tramway is well covered in the following magazine:
The Ikeda Mine was owned by a Japanese fishing company and they used, for whatever reason, largely manual methods for almost everything. The ore has mined with picks and hand drilled explosives, the ore cars at the mine were hand-trammed, the ore was "concentrated" for shipment by hand-picking the ore, the 36" gauge flatcars with the sacked sorted ore were hauled to the shore by horses and the sacks were emptied into the bunkers by hand. To transfer the ore from the bunkers into the passenger/freighters there was a Minimum Gauge tramway that ran along both sides of the bunkers and then out to a folding platform where the ore was dumped into the ship holds. The mine was purchased by Vancouver interests around 1910 but plans to install a modern concentrator and locomotives were interrupted by World War I, although a steam winch and pneumatic drills were installed at the mine. The mine closed permanently shortly after World War I due to the economic recession.
Here is the folding platform with cars tipping ore into a ship hold:
Judging by the size of the men's boots, the tramway was likely 18" gauge, although cars of this type were supplied in all even gauges between 16" and 36" with 18" and 24" being the most common in B.C.
The cars are TRUAX Automatic Cars manufactured in Vancouver by Vancouver Engineering Works. A similar car can be seen at:
The cars appear to be equipped with link & pin couplers for horse haulage or for use in small trains; this was an optional upgrade to these cars and may indicate eventual plans to mechanize the process.
According to the Mines Report of 1910 the bunker could be emptied in one 10-hour shift...using cars of between 1/4 and 1/2 yard capacity this means 1000 to 1500 car loads in 10 hours...roughly two cars tipped into the hold per minute for ten hours.
This photo shows an ore car being loaded from the bunkers. Note that the bunker is made from hand-hewn timbers about 12"x12" and that the curved supports are crafted like ship's knees from stump wood. The nearest sawmill was 2-3 days sailing away and it was not economic to ship timbers this large.
The next photo shows a passenger/freighter being loaded in the bow hold from the fold-down platform. You can also see the connecting wharf between the bunkers and the passenger and freight wharf, the corner of which is visible in the foreground.
Here is a photo of a freighter being loaded in a stern hold. The passenger and freight wharf with its 36" gauge spur is in the foreground:
Here is the wharf seen from the sea with the folding platform raised. You can also see the approach trestle for the 36" gauge tramway and the level where the 36" gauge tramway went onto the passenger/freight wharf.