Thread: Hand operated trailer mover

Forgot there is this video below showing the noise the original mover makes its very loud and uninmaginable using that at 3am to load the boat up while my neighbors main bedroom is 2 meters from my driveway

https://youtu.be/rTxCv_nFh1I

Originally Posted by gazza2009au

...... so i got confused with those huge numbers when a car is only 300nm at the wheel

A small car may have 300Nm at the wheel in top gear. at max torque revs, but I doubt it. It would be more like 3 or 4 times that! Still in top gear!

In first gear, the assumption being that you would move it around your yard in 1st, the torque at the drive wheels will be: engine torque x 1st gear ratio x diff ratio.
So let's say an average car engine makes 300Nm x (1st gear ration of 4:1) 4 x (diff ratio of 3.5:1) 3.5 = 4200Nm at the axle.
Then the force at the wheels is (axle torque) 4200Nm / (half wheel diameter) 0.38m (for radius or force arm) = 11,000N = 1122kgf, so about 6x the force you measured to move your trailer.

Wow that's huge i always assumed the rating was the maximum output

Does anyone have any input on a gear box design for the gearing that will be the lightest design but maximum strength?

I was thnking of placing ghe 3 gear sets in a triangle shape in a square box using 3-4mm sheet/plate steel

Originally Posted by gazza2009au

Wow that's huge i always assumed the rating was the maximum output

It is… At the engine flywheel.

Maybe buy Tesla plenty of juice then

Originally Posted by gazza2009au

Does anyone have any input on a gear box design for the gearing that will be the lightest design but maximum strength?

I was thinking of placing the 3 gear sets in a triangle shape in a square box using 3-4mm sheet/plate steel

Some electric motors can come with a worm drive. Simple, relatively cheap and you may be able to bolt the wheel(s) straight to the output shaft.

Originally Posted by jhovel

Some electric motors can come with a worm drive. Simple, relatively cheap and you may be able to bolt the wheel(s) straight to the output shaft.

I looked at those buy could not workout if there rating in NM was at the motor or the output shaft

Got my sprockets today im going to go for that triangle config as pictured it should keep the gearbox tight and small in size

I went with 428 pitch chain and sprockets and i will be using 20mm shafts for the gearbox unsure on a axle size yet

I double checked the 1000watt motor and it puts out 4nm at 48volt it cal also run at as little as 11volts unsure if im going with a motor kit that comes with a speed controller and thumb controlled variable throttle or if to just wire it up on/off to a 12-13volt lithium lifepo4 battery

If i get a couple small wheels from bunnings with axle bearings do you think i could use perminant loctite to lock the axle to the bearings and bearing to the hub?

Will that hold under the load? It will cut out a lot of fabrication and welding

Originally Posted by gazza2009au

If i get a couple small wheels from bunnings with axle bearings do you think i could use perminant loctite to lock the axle to the bearings and bearing to the hub?

Will that hold under the load? It will cut out a lot of fabrication and welding

Will those wheels transmit 4000Nm in terms of traction? or will they just spin in the dirt? or will they spin the tyres on the rim and rip off the valves?
I think you will need wheels of a small quad bike...

Yeah your right Jhovel im going to use the wheels off my other trailer mover and buy some hubs this time instead of fabricating my own i will just need to drill out the 17mm spline hole to 20mm, searching now for a 20mm drill bit

I purchased the correct hubs for my wheels once they arrive i need to do some drilling, the hub centers or splined 17mm so they need drilling out to addapt my 20mm all round drive shafts and axles

The small sprockets are 19mm inside diameter so i grabbed a 20mm drill bit from CTool on ebay he usually has high quality drill bits

The actual frame i need to get laser cut from 5mm plate steel if its available so its an order job

Motor hasn't been picked out yet still deciding to go 500watt dc, 1000watt dc or if i want to venture into 220-240v ac

My old trailer mover will be getting used shortly so i can go wet a line and loose some monofiliment

This is how the gearbox will be made, here are the gears all chained up

The little sprocket on the right will be connected to my motor/input sprocket

The big sprocket on the left will be my final drive gear the drive shaft will be welded to that sprocket

Gearbox will be around 55cm wide and 15cm high the gearbox will be half closed/half open to access the chain

I plan on shimming the drive shafts with M20 washers and applying grease before assembly, i may still use pillow block bearings or i may run oilless bushes

Received my steel today to build the chassis of the gearbox just need to assemble the drill press and get some good weather to start welding

All the material is 6mm