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Your Own Design / Re: Chris's Slew-Crowd Engines
« Last post by crueby on Today at 05:59:23 PM »Things are cranking up over at the Crueby Steam Shoppe. Why two slew gears on some of these, were there two slew racks as well on some shovels?Most steam shovel brands used a split boom with the chain running up the center, like on this Marion:
The crowd engine has a small spur gear on either side, to engage in the larger gears on the shipper shaft. Here is a view of the CAD model, easier to see the parts:
There is a gear rack on each side boom, and the shipper shaft (with the big gears) has two small spur gears, one for each side. This gives a nice big gear reduction for the crowd engine. The gear set on either side gives a balanced force, so no tendancy for things to twist.
On the Thew, they had a single boom running in a squred tube sleeve, with a single gear rack, like this:
The single center gear on the Thew engine engages a larger gear on a shaft with another small gear on either end, engaging in the larger gears on the shipper shaft, with a single wide spur gear driving the rack.
All gives the same end result, big gear reduction from the engine. For the horizontal crowd version of the Thew steam shovels, the same engine was relocated back farther on the boom assembly to drive the chain that ran the dipper back and forth:
The Thew also used the same style engine for the slew (right side in this next picture) and the hoist (left side), just a scaled up version for the hoist:
Neat stuff!
