Some Operating Accessories provide more train operating actions than others. Here a few examples.
The Lionel 3482 Milk car and platform is very popular with all and especially kids. The Lionel 3482 Milk platform is so popular with the kids that visit my layout I have two Milk platforms installed. It lets them hand load up the car by hand with milk cans and then discharge them to the platform over and over. Of course, the empty Milk car can go for train ride before being hand loaded again, a limited action.
By contrast the Lionel 3656 cattle car and platform cattle pen allow the cattle car to discharge the cattle to the cattle pen. Then the cattle pen can allow the cattle to be loaded back into a cattle car. The fact that both the cattle car and the cattle pen can both load and unload cattle make them the better accessory for train operations. Trains, with each having a cattle car, can allow a cattle car to be unloaded to the pen and go on its way. Then another train, with a loaded cattle car can go the cattle pen and unload their cattle. Thus, the cattle pen and cattle cars can give several train actions at the cattle pen.
Another interesting accessory operation can involve two operating accessories and a dumper car. I have a Lionel 6-12774 Log Loader Building that has been automated to dump logs remotely. The building is at the mountain that is a source of logs for the log loader building. The log loader building dumps logs to a Lionel 9303 Log Dumping car, or a Lionel 16664 Coal Dumping car, both of which are capable of dumping logs on the log platform of a Lionel 464 Lumber Mill. The older Lionel 3451 Log Dumping car is too low to be used to discharge logs to my Lionel 464 Lumber Mill log feeding platform. The Log Dumping car is transported to the Lumber Mill. The Lionel 9003 Log Dumping car dumps logs on to the 464 Lumber Mill log platfrom. Lastly the Lumber Mill saws the logs into Lumber and is discharged to the Log platfrom.
Log Loader discharges logs to log car, Log car transported to Lumber Mill by Train
Log Car discharges Logs to 464 Lumber Mill Platform
Lumber Mill saws Logs to Lumber
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