According to the 2016 H-D Service Manual for Trikes, the axle cover set screw torque value is 60-84 inch lbs.
For the front axle nut, the torque value is 70-75 foot lbs. The front axle pinch screw is 18-22 foot lbs.
If you are doing any of your own work, I'd suggest buying the factory service manual. For the trikes, you need the Touring manual, and trike supplement.
.....the HD factory service manual have a wealth of information.....get a parts book also.....and of course you have to have a for the year of manufacture service manual....