Just before bag, one of our banebot 775 16:1 gearbox stopped working. The motor is still working but the gearbox shaft is no longer spinning. We didn’t have time to take off the gearbox to address the problem. Does anyone know what is wrong so we can go into competition knowing what to fix? Thanks
I’m thinking it might be something along the lines of the pinon on the motor isn’t quite on the output shaft.
Regardless of the problem I recommend you order a new gearbox and motor assembly and just swap them when you get to competition. After that you can take apart the gearbox you took off and figure out the issue knowing that you can play.
The pinion has probably slipped on the motor shaft. It happened to one of our 775’s during practice this past weekend.
At a minimum, you’ll want to order a couple of extra pinions from Banebots. They’re only a couple of dollars each, and they ship the pinions out quick, usually only takes a couple of days to get them.
The old pinion is most likely wallowed out and ruined. Hopefully the motor shaft isn’t galled up and you can just press on a new pinion.
Did you grease your gearboxes before assembling? Ungreased gearboxes can quickly turn into metal glitter.
Steps for using banebots gearboxes:
1: Grease your internals and assemble
2: Run your gearbox for about 15-20 minutes. Or in 10 minute periods
3: Disassemble
4: Clean
5: Re-grease but do NOT overgrease. White lithium may be a little too thick so I usually just scoop some grease from FP gearboxes and drop it into the banebots gearboxes.
6: You should be good to go
Gear dust + thick grease without going through this process will bind up your 16:1 gearbox.
Is it bad that I am using white lithium grease? It’s the only grease my team has. And do we need to disassemble the gearbox so often?
Use it in moderation. You only need to take it apart twice. Once to do the first application of grease then again after you break them in and have to clean/regrease.
When I grease the BaneBots, I actually will run them for about 45 minutes after greasing. I start with a low voltage and gradually increase it until the motor runs steadily at 12 volts with about 1-1.5 mA.
Note: if at first the motor has trouble starting to rotate, try manually spinning it with some force to get it started.
As for number of runs, depending on the gearbox ratio, run the motor about 2-3 times.
Hope this helps.
Get your hands on some LocTite 603 “green” Retaining compound. Use a Q-tip to coat the inside of the pinion gear before pressing it on. You have to install the pinion quickly and in one step otherwise the compound will cure and lock the pinion in place part-way through your install making it impossible to press it further onto the shaft. Be very careful to use it sparingly and do not get any on the motor’s bushings. One of my teams’ sponsor is a snowmobile repair and recycling company and most snowmobile (2-stroke) crankshafts are made in multiple pieces all pressed together hand held purely by interfereance. This compound is used with each press fit to lock the components together. It will not release unless it is heated. It is an excellent product and I use it religiously on interfereance fits.
Do you have any tips on pressing on a pinion gear as we don’t have a machine press. We put on the other one with a hot plate and hammer.
That might be part of your problem… A bent shaft or misaligned pinion can wreak all kinds of havoc on a gearbox.
Ask local machine shops – someone is bound to have a press that either you can use, or they will use on your behalf.
If you don’t have a shop press, you can make your own using a hydraulic bottle jack like this one: http://www.princessauto.com/pal/product/1010006/Air-Hydraulic/6-Ton-Bottle-Jack. (Maybe a mentor has one at home or will let you use one from a spare tire kit in a car. - Toyota trucks have awesome little bottle jacks although they are mechanical and not hydraulic, they will work as well).
Simply make a frame out of some beefy steel and place the bottle jack inside. When you actuate the jack you can press things together between the jack and the frame of your home-made press. A 6-10 Ton bottle jack can be found at places like Harbour Freight (USA)/Princess Auto (CAN) for about $20-$30, (I bought a couple 20 Ton ones on sale for $19.99) and some heavy scrap steel can be used to make an excellent frame
If a bottle jack isn’t for you however, you can try the following. I don’t like using hammers because they can often mushroom and distort metal shafts and gears. If you have a good-size vice it will work well but getting everything aligned can be trickky. Place the motor and pinion in the vice with the pinion aligned with the shaft. Make sure you are pressing between the pinion gear and the motor’s shaft that pokes out the back of the case, not the back of the motor or the contacts. Make sure the vice is a good quality unit with square jaws and will not start to skew once you begin to apply force. use the jaws of the vice to press the pinion onto the shaft while carefully observing the alignment of everything. Make sure things don’t start to bend or skew and realign if needed. be observant of how far the pinion has been pushed onto the shaft as when the pinion has made it all the way onto the shaft you will be essentially be squeezing just the shaft of the motor and it will certainly bend if you keep applying force. If you have to press the pinion further onto the shaft, use an object like a washer or nut as a spacer to apply force to the pinion while letting the shaft poke out the end. I personally don’t like using heat to install things like this because the heat makes the metal more malleable and easier to bend/distort. With a press-fit, heating the item too much can cause it to deform permanently while pressing it on thus reducing the effectiveness of your interferance fit. The retaining compound is good because it will help act as a lubricant while the parts are being pressed together and will lock up when you stop. Make sure you buy several motors and pinions as replacements and install the pinions and any backing plates on your spares before the competition. You don’t want to have to muck around with limited tools and time, pressing pinions onto motors when you are rushing to get your machine back on the playing field.
Good Luck
You don’t need a press to put a pinion on a 775 or smaller motor.
Any decent vise will do it easily.
Make sure the rear end of the MOTOR SHAFT (very important!) is resting directly on one jaw. Use a piece of aluminum or steel scrap between the shaft and the vise jaw if the electrical terminals are hitting the vise jaws.
Place the pinion against the other vise jaw and line it up with the front end of the motor shaft. MAKE SURE THAT THE ONLY POINTS OF CONTACT WITH THE VISE ARE THE REAR OF THE MOTOR SHAFT AND THE PINION. SLOWLY tighten the vise until the pinion is where you need it on the shaft.