Deep fins increase surface area for improved heat dissipation, while exclusive drive spines are knurled and burnished. The shaft surface resists slippage caused by heavy torque loads and assures longer bearing life. Top-quality bearings ensure longer life and quiet, smooth running. A special silicone fluid inhibits heat build-up to prolong service life. A bi-metal thermostatic spring adjusts the fan speed in response to operating temperature requirements - reducing fuel consumption.