Posted March 2, 20214 yr Hi everyone, I've finished trying to RC my 42043 and it seems that the PF L motor has issues providing sufficient power to drive the set? I obtained instructions from the creator of this video (https://www.youtube.com/watch?v=BpP_05uxKqs&t=22s&ab_channel=PawełWojnarowski) and also checked PPUNG DADDY's 42043 RC video (https://www.youtube.com/watch?v=O8easq7ueIo&ab_channel=PPUNGDADDY(뿡대디)-LEGOTECHNICRC), both used an L motor with no problems. Here's a video of the issue: https://youtu.be/J8P13WLPzN8. As you can see in the video, the motor loses power after driving for some time, eventually being unable to drive at all. The problem is worsened when I try to drive and steer at the same time, it's almost impossible to drive and turn. I have tried swapping the tyres around, changing batteries, trying a V1 and V2 IR receiver, switching positions of the motor and servo cables, and using a new L motor. But the problem still persists. Here's a photo of the L motor: Could it be because of excess friction introduced in the rear axles during construction? Because I noticed when I lifted up the rear axles, the motor spins the wheels at its standard rpm, BUT only 1 wheel on each axle spins, the other is stationary. Then when the wheels contact the floor, the motor suddenly seems to struggle with driving the thing. Hence I was thinking could it be that I built the differential too "tightly"? Appreciate any help from the technic experts in this forum, thanks in advance!
March 2, 20214 yr If you know that you have built it too tightly, then try slackening everything off a bit. That does seem an awful lot of weight for one L motor to try and move, especially without significant down gearing. If you're not using brand new alkaline batteries and a V2 receiver, I would expect it to struggle as you're seeing. You'd lose speed but gain torque by using the new differentials and 12z gears to drive them.
March 2, 20214 yr Hello @kai836 and welcome to the forum. The issue here is the relation of power, torque and rpm. The relation is quite simple: Power = Torque x Speed (rpm) The motor is directly connected to the wheels without any transmission, so it can only run with very low rpm at the beginning. Therfor the given torque is not high enough to power the truck from standstill. When you steer, there is an even higher force against the movement, thus stopping your truck. When there is no load applied (you lift the truck), you can see the real speed of the motor with the freely spinning tire at high rpm. You need to gear down the motor to enable it to apply its power. Edited March 2, 20214 yr by Jundis
March 2, 20214 yr @Jundis, reckon just changing the diffs would be enough? There's not space for much else.
March 2, 20214 yr Author @Jundis@amorti Thanks for the welcome and prompt replies! Hmmm, I did think of gearing down, but I was hoping to achieve the same speed as the videos I referred to. How is it that it worked fine for them and not for me? I'm pretty sure we all used the same steps... I guess it could really be down to the construction of the rear differential and axles?
March 2, 20214 yr @amorti Ups, did miss the first video link. Yeah, stronger/better batteries will help. But als the use the new diff will help:
March 3, 20214 yr Author @amortialright, I will give that a try. Thanks! @Jundisok I will try this out, do you know what's the name/part number of the red gear and grey casing? Thank you!
March 3, 20214 yr Components are: - 65414 (Housing) - 65413 (Red gear) - 6589 (bevel gears, 5 of them) An you need a smaller double bevel gear 6589 to drive them. As the diff is quite new, you can maybe order them directly at Lego: https://www.lego.com/en-gb/service/replacementparts/sale/choose-brick
March 4, 20214 yr If all the options above don’t help, just try if the wheels aren’t pushed too far on the axle so that they create friction between the rim and the connector that keeps the axle in place. I did exactly the same configuration as you, so I don’t think it’s a gearing issue. Just make sure the wheels aren’t too thight pressed on the axle.
June 28, 20213 yr Author Hi everyone, thank you for your kind help. I've managed to solve the issue by using extra strong batteries!
September 1, 20213 yr On 6/28/2021 at 4:56 AM, kai836 said: Hi everyone, thank you for your kind help. I've managed to solve the issue by using extra strong batteries! What's name of batteries ? Thank you
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