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Ari Holopainen / useful | |
| USEFUL STUFF A. Shift lever position locking:
Here is shown some shift lever position locking methods that are useful in sliding axle gearboxes. Almost every auxiliary gearboxes (splitter and range-change units) that I use in Lego constructions have sliding axle solution. A.1. Version I: The first one is also the simplest. The idea is that you first rotate shift lever out of its locking point and then you can slide the sliding axle in new position (new gear). Finally you turn shift lever in opposite direction and lock it in new position. Shift lever has a direct connection to the sliding axle in this version.
A.2. Version II: Version II is better than the first version (described above) in two ways. Firstly, shift lever is not directly connected to the sliding axle so the distance between the shift lever and the sliding axle is adjustible. It helps to locate shift lever in desired place. Secondly, shift lever connection needs only one Lego unit space if it is located next to a gear wheel. Note that three locking positions is not a real improvement, it’s possible in the first version also.
A.3. Version III: Version I and II are not very user-friendly because you have to unlock shift lever before you can change gear and finally you need to relock shift lever. This 3rd version has an automated locking method so all you need is pull or push shift lever in gear changing. Shift lever position locking is done by locking pin and rubber belt. Normally locking pin stays down between two Lego-studs. When you move shift lever, locking pin must jump up against rubber belt before shift lever can be moved. This means that you need some force before you can move shift lever in next gear. When next gear is engaded locking pin has new position and now it stays between another two Lego-studs. It also means that gearbox can’t accidentally change gears when driver doesn’t touch shift lever.
A.4. Version IV: 4th version doesn’t have a auto-locking mechanism so it’s a little stupider than 3rd version, but it has a new shift lever position locking method. This time shift lever becomes unlocked when you just pull it upwards. Then you can slide shift lever (and sliding axle) forwards or backwards to engage next gear. Finally you drop shift lever down into this new locking position.
In this case there is not any rotation with shift lever, so you need one ridig axle to support shift lever device in right direction. B. H shift pattern:
Shift levers or shift patterns are usually not modeled in my gearbox pictures but they are included in YouTube videos called Building example. Here is one way to build H shift pattern for the synchromesh main gearbox. This setup works in situations where synchro axles are supported by parts called brick 1x2 with holes. So this 4-speed shift pattern is 3 studs wide and parts brick 1x2 with holes and brick 1x1 with hole are used to get plate 1x1 into right place between shift lines.
If synchro axles are supported by longer bricks 4-speed shift pattern becomes 4 studs wide with half studs empty space on both sides. In this case you need brick 1x4 with holes to get plate 1x1 into right place in the middle of the shift pattern. And 2x bush 1/2 are used to limit shift lever’s movement sideways. I have modeled shift levers and shift patterns in studless versions so they are not included in this page. At the moment best studless shift pattern is in 4-speed version IIB personal car transmission. In other studless versions shift pattern is larger and less accurate so it’s worth to check that 4-speed gearbox. Note: Shift lever part slides on the axle, but I prefer to lock it in the axle and slide the axle instead. With this arrangement shift lever can be moved sideways much smoother than in original purpose of use. [Back to main page] |
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