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Round-Trip EF66 (1976)

The Round-Trip or Reciprocating EF-66 was first released in a third-generation liftoff box like other early Round-Trip Plarail engines. This liftoff box release was quickly replaced by a fourth generation "train" box individual release. An updated gearbox design appeared when the EF66 moved from fifth generation boxes to sixth generation boxes around 1987. At the end of Japanese EF-66 production in late 1992 the EF-66 lost its reversing ability as it was converted to use a normal new power gearbox for Thailand production. More details on the differences between the two gearboxes can be seen on the Round-Trip repairs page. A peg hanging down from the gearbox slides part of the gear train over to make the engine reverse when it hits special trigger tracks, with the next hit sliding the gears back into place and reversing the engine again. This concept was also used in the Tomy Trains range of exported Plarail-like train sets. The metal bar on the back of the locomotive takes the place of the normal coupling system and it is supposed to be able to collect cars and then reverse and drive away with them, although this operation is hard to get working properly in practice.

EL-02 EF-66 Round Trip (1979)

The fifth generation box EF-66 Round-Trip (EF-66おうふく) was produced throughout the 1980s and features an earlier design of gearbox with enclosed drive tires. Like other individual EF-66 releases, it has a single rear coupling bar and a front power switch as opposed to the side power switch of the version used in sets with a front coupling bar.

The underside of the locomotive shows a plastic plate where the front metal coupling bar would be installed on the two-bar version and the protruding pin which is slid from side to side on reversing tracks to reverse the gearbox. There is no electrical switching to reverse, just the mechanical changing of gears inside the gearbox. The round-trip EF66 has no normal activation tab, making it incompatible with many accessories that use the activation tab system. The earlier EF66s use a slightly older style of drive wheel with no additional plastic ring on the outside face.

I have a second Round-Trip EF-66 with older gearbox, but the chassis was cracked in multiple places and one of the body shell clips was missing. I ended up using components from the gearbox to put reversing functionality back into a Hong Kong-made C12 gearbox.

Round-Trip EF-66 (1987)

Later on a slightly revised gearbox and chassis were developed. The external molding was virtually unchanged, with the same color scheme and single rear coupling bar as well as bent-up front power switch. The rear drive tires have an additional ring in the molding as well. This EF-66 was produced in a sixth generation box as 往復EF-66 (Round-Trip EF-66) until the end of 1992 when the molding moved to Thailand and was updated to use the new power gearbox without reversing features.

 The gearbox output tires have been moved to the outside of the gearbox (and on this example have been replaced by shaved down rubber pulleys as described here) and there is an additional protruding support to keep the C battery in place inside the chassis. My sixth generation new gearbox EF-66 was produced in September 1992, towards the end of Round-Trip production.

I did not know this, but apparently there was a regular old power release with no reversing gearbox released at some point. I think it must have been released right after Round-Trip production ended, as I do not believe old power EF66s were ever produced in Thailand. An old power non-reversing EF66 can be seen on this webpage (along side several other EF66 variations) on the Mie Battery Railway website.

After the EF-66 tooling was moved to Thailand and redesigned to use the new power gearbox, it was released in a late sixth generation box around 1993 as EF-66 Electric Locomotive. This version was rereleased in a seventh generation box beginning around 1994 and discontinued in 2003 when it was replaced by the updated K-03 EF66 type 11 in a more realistic JNR blue livery and slightly later K-08 EF66 type 12 in a freight livery.