Rayballistae are most effective when connected to an external power supply of some sort. The most common way to do this is to use a force conduit to link it to a spinorb. If the rayballista is mounted on a hovership then the weapon is connected directly to the ship's power supply. If the weapon is not too large compared to the size of the ship, this can result in a very high rate of fire, comparable to a semi-automatic firearm.
Reloading mechanisms vary, but the simplest and most reliable consists of a sliding block that moves along the upper surface of the stock. A hole through the block permits the bolt to pass through it. When the block is pulled back, it pulls the string back with it. As it does so, a mechanism inside the block grabs the bolt and pushes it back against the string. When the block returns to its forward position, the weapon is ready to shoot. Several different mechanisms can be used to pull the block back, such as a rack-and-pinion or a series of levers connected to a crank. The exact choice of reloading mechanism depends on the power of the bow and the anticipated rate of fire of the installed weapon. Regardless, the mechanism must be very rugged and usually contributes a significant fraction of the weapon's weight.
The most common use of the rayballista is as the primary weapon on a windchariot. In this case, the weapon is relatively light (5-6 feet long and 70-90 lbs weight is small for a rayballista) and designed for a high rate of fire.