Abstract: More reliable torque motors are provided with reduced susceptibility to external vibration while also maximizing structural damping without requiring the usual potting with resins and adhesives, bolting hardware, etc. Enhanced torque motor dependability is achieved by clamping torque motor assemblies rigidly in place through frictional forces generated by a generally thin walled tubular housing preferably having surface elevations which compressively engage the motor assembly through an interference fit. The more reliable torque motors are especially useful in aviation applications as actuators for servovalves, and wherever highly reliable virtual fail-safe performance is required.

Abstract: A high temperature refractory brick wall is repaired by removing and replacing damaged brick while the wall is maintained at a temperature below normal operating temperature but sufficiently high to avoid damage from contraction resulting from cooling. New brick having a coefficient of thermal expansion compatible with the heated wall are used to avoid cracking of the wall due to expansion during heat-up. Workers wearing protective clothing, preferably incorporating a circulating fluid cooling system, remove the damaged brick and install new brick in their place in walls having surface temperatures of about 500.degree. F. or higher and internal temperatures substantially above 500.degree. F., preferably at least about 1500.degree. F.