In my current worldbuilding project, humans find themselves struggling to survive on a cold, dead world with minimal sunlight and the aid of magical machines called "spinners". Spinners are two identical cubes adjoined by a face, always counter-rotating w.r.t one another at a constant rate. No amount of ungodly toque can slow their rate of counter-rotation, betraying unlimited, tappable work.
People use these machines for generating heat and powering machines and vehicles. My question is, what is the best way spinners may be incorporated into the design of a rocket engine? (Couple notes: the fastest spinners rotate at around ~1 Hz which, due to their unwillingness to be slowed by counter-torque, can be geared-up to hundreds, thousands, or hundreds of thousands of Hz by a gearbox; the engine need not necessarily have a thrust-to-weight ratio of 1:1 or greater--the focus is maximum delta-v.)
This sort of perpetual motion won't necessarily get you off the ground and into orbit for free. Rockets will still need exhaust to push on to generate thrust in a vacuum. So, spinners neither eliminate the need for fuel nor the tyranny of the rocket equation.
My knowledge of rocketry is weak, but I imagined a spinner-powered thermal device could be used to heat some propellant, say, liquid hydrogen, up to a few thousand Kelvin like in a typical nuclear thermal rocket, except the nuclear energy doing the heating is replaced by this spinner-powered thermal device. The thermal device could work by forcing a great deal of electricity through many tightly-wound metal coils (the spinners would be used to generate the strong rotating electromagnetic field). The friction in the coils would heat the propellant and so on. However, I don't think there is a metal or metal alloy that doesn't start vaporizing above ~2000 K (probably less than that, actually). At that point, one may as well forget about spinners and use nuclear elements instead.
Is what I suggest feasible? If not, is there another way to feasibly incorporate spinners into rocket technology? (I don't want to continue with the development of my world into the off-world without knowing the applications of spinners in space.)