After the post yesterday about tractor engines vs vehicle engines, I found the following definitions on the Caterpillar website. Most of our old antique tractors don't fit into these categories because the ratings system has taken years to develop. Especially when asking for certification by the American Bureau of Shipping, Det Norske Veritas, or Lloyds of London insurance, the ratings are followed.
The principle difference in the ratings are based on average life to overhaul. Life to overhaul is predicated on strength of materials, RPM and load factor. Most gasoline vehicle engines are considered "light duty", and cannot approach the life to overhaul of even "medium duty" engines.
Diesel Engine Rating Definitions excerpt from Caterpillar Industrial Ratings Guide:
Explanation of Ratings A, B, C, D, and E:
For an exact determination of the appropriate rating, contact your local Cat dealer. Engine rating obtained and presented in accordance
with ISO3046/1.
IND-A (Continuous)
Continuous heavy-duty service where the engine is operated at maximum power and speed up to 100% of the time without interruption or load cycling.
IND-B
For service where power and/or speed are cyclic (time at full load not to exceed 80%).
IND-C (Intermittent)
Intermittent service where maximum power and/or speed are cyclic (time at full load not to exceed 50%).
IND-D
For service where maximum power is required for periodic overloads (time at full load not to exceed 10% of the duty cycle).
IND-E
For service where maximum power is required for a short time for initial starting or sudden overload. For emergency service where standard power is unavailable (time at full load not to exceed 5% of the duty cycle).
The principle difference in the ratings are based on average life to overhaul. Life to overhaul is predicated on strength of materials, RPM and load factor. Most gasoline vehicle engines are considered "light duty", and cannot approach the life to overhaul of even "medium duty" engines.
Diesel Engine Rating Definitions excerpt from Caterpillar Industrial Ratings Guide:
Explanation of Ratings A, B, C, D, and E:
For an exact determination of the appropriate rating, contact your local Cat dealer. Engine rating obtained and presented in accordance
with ISO3046/1.
IND-A (Continuous)
Continuous heavy-duty service where the engine is operated at maximum power and speed up to 100% of the time without interruption or load cycling.
IND-B
For service where power and/or speed are cyclic (time at full load not to exceed 80%).
IND-C (Intermittent)
Intermittent service where maximum power and/or speed are cyclic (time at full load not to exceed 50%).
IND-D
For service where maximum power is required for periodic overloads (time at full load not to exceed 10% of the duty cycle).
IND-E
For service where maximum power is required for a short time for initial starting or sudden overload. For emergency service where standard power is unavailable (time at full load not to exceed 5% of the duty cycle).
