The use of a wheeled "cart" of some sort to enable the easy transport of an assembled telescope has been discussed at various times around the forum. One can purchase this sort of thing, but I figured I could do as well, or perhaps better (more tailored to my situation), by doing it myself. What follows is a discussion of what I did and why, in the hopes it might help others do the same. Or, perhaps give some ideas on what to look for in a commercial unit.
My telescope is an 8" f/5 Celestron Newtonian with attachments, on an AVX mount. My situation is that I can't image from my home, due to the strategic (aka poor) location of trees and structures. There's very little view of the sky from anywhere I can put the telescope in a protected area, where it can be left out over night, so it must be moved, attended, and removed with each session. The best viewing place is across the street, on my neighbor's driveway. Not relishing the idea of disassembling and reassembling the scope every time I want to view, the answer was to put the fully assembled telescope on wheels.
The idea was to build a T-shaped platform to sit the telescope on, with wheels at each corner. I used 1x4 lumber for this, made slightly longer than the telescope mount's legs in their collapsed position. Top of the "T" went across the "front" of the mount, with the leg of the "T" heading to the back. The surface of the platform can be used to hold stuff like the PowerTank.
The wheels on the two ends of the "T" are 8 inches in diameter. They are pneumatic (not solid), but don't need to be filled. The first iteration of this used 4" wheels, which were both too hard, and too small, causing a lot of vibration during the journey, and with a susceptibility to getting snagged on small rocks. The tail of the T still has a 4" wheel, because it needs to be on a swivel and lock in position. The 8" wheels have a sealed ball bearing tube in the center, and are held on with large bolts acting as a half-axle. "J" bolts hold the axle bolts in place. I put washers on both sides of the wheel to act as bushings, just in case, and to control separation between the wheel and the wooden platform.
From the top, the telescope tripod legs sit in small wells that I drilled into the wood, to keep it from sliding off. String holds the whole thing in place, but is easy to remove if I need to take things apart for transport in the car.
Here is the "tail" wheel, which has the locking lever. The different wheel sizes, offset by the different mounting positions, results in an almost identical height above ground for all three corners, keeping the overall tripod pretty much level.
I also added "Leveling jacks" to each corner, in order to both stabilize the mount from vibration and movement (the wheels are soft), and to level the overall telescope for the slight incline of the driveway. In use, the screw head rests on a block of 2x4 lumber that sits on the ground. I lift the end of the platform up, and adjust the lower nut until it's in place, then hand-tighten the upper nut to stiffen the assembly. I've not found wrenches to be necessary. In hindsight, I should have made the tail longer, so that its leveling jack would be on the outside end, away from the wheel's locking lever, or positioned the jack closer to the center. As it is, they interfere when pulling the telescope backwards. Not fatal, just a little annoying.
In order to know when the telescope mount is level, without removing the rotisserie and everything above it, I created a "proxy" on the tripod, adjusted such that when the proxy is level, so is the top of the tripod. It consists of a thin piece of wood, attached to the base with long-ish screws in 3 places, with springs underneath. The leveling jacks are adjusted to level the tripod, then the three screws are adjusted to make the proxy level in both directions. In operation, I put a small level on the proxy, and adjust the leveling jack screws until the proxy is level. When it is, I know that the mount is level too.
I think that's mostly it. I basically hold on to the mount's Elevation adjustment knob and one leg when "driving" the whole contraption across the street, swing it around so it points north, and lock the tail wheel in place. Then the jack screws get adjusted for level, and the telescope is ready for polar alignment. I have not found the overall unit prone to tipping over, though I am very aware how heavy it is, and could of course have made it both wider and longer if that had been a problem. Driving across the rounded curbs we have here is done very slowly and carefully, with a very firm grip on things.
Yea! Besides the cross-street trips, the contraption is also useful at public events, where the telescope setup is some distance from parking.
Comments and questions are welcome, and good luck with your own construction.