need comma help.

[market]

i have two phrase that i'm having trouble with.

1. They walk out on deck ( ) carrying small gages. ( i think there goes a comma, but i could be wrong)

i think there could be a comma because i can phrases it like this:

2. They walk out on deck and carry small gages.
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the other one is.

3. The truck rams the car, sending it careening down the exit ramp.
(i'd say yes , a comma.)

[Humble]

Hi, Market,
It's a good question. I think if a participial clause refers to the last word, we don't need a comma; if it refers to all the main clause, we do. I wish I were sure.
There are some jokes based on the absence of comma.

[Tdol]

I don't see the need for the comma in the first. The second describes the consequence of the ramming, but the first describes the subjects as they came onto the deck.