Oh! I am a coat of steam, up to high pressure, and, like a coat of horse, I must be w

Oh! I am a coat of steam, up to high pressure, and, like a coat of horse, I must be worked up to a certain amount of power, or I become useless. I am, in fact, a working coat of steam, and must be worked up to 100 pounds of steam, or I can no longer be worked up to a certain amount of power, and must be taken off. I am, in fact, a working coat of steam, and must be worked up to 100 pounds of steam, or I can no longer be worked up to 100 horse power.