The screws contain electric motors that are responsible for accelerating the screws and flywheels to operational speed. As the screws and flywheels are supported by magnetic bearings and as they spin within an evacuated environment, they will experience very little friction. However, as no electric motor is perfectly efficient, some heat will be generated by these motors. Since the screws are in a vacuum, they cannot dissipate heat through convection. The claim is that this heat will not build up within the screws because it can be transferred from the motors' stators to the evacuated tube wall, and from there it will dissipate through the wall and into the environment.

The motors are mounted on brackets that contain channels through which coolant circulates from the motor's stators to the tube wall to carry heat away. The brackets are welded to the inner surface of the steel tube, so there are no through-wall penetrations that could compromise the tube's ability to maintain a vacuum. Redundant coolant circulation pumps, which are designed to be easily swapped out by a robot in case of unit failure, circulate the coolant through the system.

The flywheels connect to the screws through electromagnetic clutches, and when these clutches activate, the flywheel's momentum is rapidly transferred through the clutches to the screws. The clutch activation time will vary depending on the speed of the vehicle and the length of the adaptive nut. At the end of the acceleration section, when the launch train is moving at 11123 m/s, the clutch activation time will be as short as 1.8 ms. (At these speeds, it might be more appropriate to describe "the clutch" as resembling the anvil-hammer mechanism inside an impact wrench.)

The amount of energy that is converted to heat as opposed to kinetic energy is calculated in the claim entitled "Momentum Transfer through the Screws to the Adaptive Nut is Feasible".

Because the clutches activate infrequently and only briefly, heat will initially be generated and concentrated at the screw-flywheel interface. It will then spread into the bulk of the screws and flywheels via conduction, bringing the interface temperature back to the average temperature of these components. However, each launch will raise the bulk temperature by a few degrees.

This heat energy must be dissipated from the screws and flywheels into the surrounding environment between launches. The heat dissipation rate and the maximum allowable operating temperature of the screws will ultimately limit the launch rate. Because the screws and flywheels are magnetically levitated in a vacuum, the simplest solution is to allow them to radiate their heat to the environment. A solution that circulates coolant through the rotating components would transfer heat from the screws and flywheels more quickly but would be significantly more complex and challenging to maintain.

Net radiative heat transfer from a surface in a vacuum:

$$P_{net} = \epsilon \sigma A ( T_1^4 − T_2^4 )$$

where:

$P_{net}$ = net radiative heat transfer rate [W]

$\epsilon$ = effective emissivity of the surface (~0.9 with coatings)

$\sigma$ = Stefan–Boltzmann constant = 5.670374419 × 10⁻⁸ W·m⁻²·K⁻⁴

$A$ = radiating surface area [m²]

$T_1$ = absolute temperature of the surface [K]

$T_2$ = absolute temperature of the surroundings [K]

For example, if $T_1 = 573 K (300 \degree C)$ and $T_2 = 298 K (25 \degree C)$ and surface area was $2\pi(0.5)(5)=15.7 \space m^2$ then the radiated energy would be

$$P_{net} = (0.5)(5.670374419 × 10⁻⁸)(15.7)(573^4 - 298^4) = 44,209 \space W$$

In the related claim linked above, the heat energy generated per screw segment per launch was estimated at 1.422 MJ. A screw segment's mass, if it is made out of steel, is calculated using the digital twin to be 5,980 kg, and the flywheel's mass is 1,224 kg. If we assume that the heat energy is split evenly between the flywheel and the screw, then the screws temperature will increase by

$$\Delta T = {Q \over mc_p} = {1.422e6/2 \over 5980 * 500} = 0.24 K$$

and the flywheel's temperature will rise by

$$\Delta T = {Q \over mc_p} = {1.422e6/2 \over 1224 * 500} = 1.16 K$$

The rate at which heat energy is deposited into the screws and flywheels is 1.422 MJ per launch. If, for example, launches occurred every 2,400 sec (40 minutes), then heat is deposited at a rate of $1.422e6/2400=592.5 \space W$. Even if the launch rate were increased to once per minute, the heat generation rate would be only 23,700 W, still well below the radiative heat loss rate (44,209 W). Therefore, radiative cooling should suffice to prevent the screws and flywheels from overheating, and there is no need to consider more elaborate coolant-based cooling strategies for these parts.

It should be noted that the screws are not spinning in a perfect vacuum, as there is still a small amount of air in the evacuated tube. The circulation of this air could remove some additional heat from the screws through convection.