How literal is this phrase?

Sample examples at http://tinyurl.com/is-it-lit

donkey engine:

Definitions:

  1. a locomotive for switching rolling stock in a railroad yard
  2. (nautical) a small engine (as one used on board ships to operate a windlass)

Examples:

  1. ! One member now has what must be the worlds largest collection of oil pumping donkey engine photographs , he spent three days with his camera in and around Oil Town ,
  2. available . This crane had its own small auxiliary engine which was known as the donkey engine and often the crane itself was called ' the donkey engine ' . So the
  3. 1 inch , with a gross tonnage of 2,042 . It was equipped with a donkey engine and an early type of midship house . W R Price & Co. eventually sold
  4. auxiliary power unit that does n't legally have to meet current European standards ( as donkey engines do not ) , but is actually given a ' tax-rebate ' to use dirtier
  5. hopper . STRONG POINTS Uses hydraulic power instead of noisy ( and thirsty ) petrol donkey engine . Treble the price of some ⠀ ˜ Poo Pickers⠀ ™ , but

Step 1: Select the definition of donkey engine which occurs most of the times in the above examples. Ignore other definitions.

Definition1 Definition2

Note: Please select the answers below carefully based on the definition which occurs frequently in the examples

Step 2: score of 0-5 for how literal is the use of "donkey" in the phrase "donkey engine"
0 1 2 3 4 5

Please provide any comments in case you want to tell us about your judgement or any other queries/suggestions! Not Mandatory but helpful.