In recent weeks, a flurry of discussion and testing has been tone surrounding the Rapido RS-18 mechanical performance. The discussion focuses on the CN version of this model. Apparently they are experiencing a failure to run within a few hours of operation. This has been blamed on the motor.
I have acquired a DC ready CN version at a much reduced price on eBay.
The seller was motivated, likely because of speculation based on this discussion. The word is that Rapido will replace the motor by request. While that is good, it is some hassle and takes the “new” out of the model.
I may end up requesting a new motor. It will depend on how things play out.
The globle plan is to run several performance tests on the model to see if any deterioration is apparent. In the end the unit will be upgraded with a rail pro LM-3S & iPhone speaker and then sold.
The plan for the test series is as follows:
1.) run a 15 minute break in test on rollers.
2.) run the standard test series on flat & level track.
While there are variations, nothing seems more than normal at this time. The old process to measure train length was used in this set of data. The new method will be used from here on. The other Rapido engines were done using the older techniques.
3.) determine the maximum number cars pulled on a 2.5% grade using the recent techniques.
The activity has been focused on putting the RS-18 through severe running conditions to see if there is any performance degradation. To do this, the unit was first run on rollers for three hours, both forward and reverse. Then the engine has been tested to determine the maximum grade and train length. This has put over six hours of testing at or near wheel slip conditions. This requires the motor to operate near the maximum operating power. This equates to heat and stress on the motor.
The grades examined so far range from zero to 9 percent. The train length examined include the weights of zero to 20 four ounce freight cars.
Thus far a complete map has been defined at 2.5 percent grade. The engine will pull the weight of 15 cars up that grade. The wheels were slipping over most of the power range. The engine would not pull 16 cars up that hill.
The following picture shows the engine working on tbe 2.5% grade.
4.) run the engine on rollers for 2 hours at 13 volts
5.) this time the focus was on how many cars the RS-18 would pull up a 4 percent grade. The testing showed that the engine successfully would pull 12 cars over a range of power and speeds. The engine wheels were spinning at all power settings for 12 cars. The engine would move 13 cars, but could not reach the top at any power. An interesting observation is that the speed at voltage reduced on a shallow trend until the wheels started slipping due to the increasing car load. After slip occurs then The speed drops rapidly. Generally, only one more car can be successfully moved up grade after wheel slip. Curves showing these results will be highlighted here and in detail on a grade train length post- watch for it.
6.) determine the max grade for engine only & for 8 4 oz cars:
The grade was increased until the engine could not successfully pull eight cars up to the top. The grade was reduced slightly to allow the engine to pull the cars. This occurred at 6.2 percent grade. This is a surprising level. The test track is straight, no curve resistance.
searching for the maximum grade that the engine only would stall was limited by the maximum grade the test section can be maintained safely. At this time that is 17.5 percent. The engine with no cars moved to the top with ease.
This condition is not very useful anyway. The last grade that was attempted with cars was 7 percent. In this case four cars pulled the static engine down the grade.
7) at this point the continuous running is greater than 20 hours. Substantial number have been at high power. A final review of the performance will be made to show whether any deteriotion has occurred.
The plan will be modified or expand based on what is seen in these results. Based on questions coming out of the grade and train length testing, several of the previous tests will be examined with a DC power supply with PWM
if the unit is still surviving, I will install a Railpro LM-3S module. Then repeat a number of steps on the Rail Pro power supply. If everything is still holding together, then selected tests will be run with my NCE DCC supply. The latter test plan is still a bit fuzzy.
thanks for looking.
