What does it mean to "pull SCVs"

I'm trying to improve my very poor StarCraft2 play and have been reading about popular build orders, rushes, cheeses, etc. In reading this guide there is something I don't understand:

http://wiki.teamliquid.net/starcraft2/Mega_Rax

Once the 4th rax has finished, pull half your SCVs and poke his ramp with your marines.

and later:

When Terran pulls SCVs, it is strongest against zerg; however Mega Rax is also the hardest to hide from zerg.

But I have no idea what "pull half your SCVs" means. Pull them off of production? And do what with them?

Thanks for any insight.


Solution 1:

Once the 4th rax has finished, pull half your SCVs and poke his ramp with your marines.

Pulling means you take them away from what they are currently doing.
So, you pull half of your SCVs away from your resources, but to do what?

This is pointed out in the next sentences:

You can first place a bunker outside his ramp to give you micro space. Once you're up the ramp, build another bunker and start targeting workers. Make sure to keep producing from your barracks and making depots.

Basically, you send some SCVs along behind your marines so that they can build bunkers and repair those bunkers, the other SCVs you have pulled are useful for supply depots and taking damage.

Every time that a SCV dies instead of a Marine when you are pushing him, it's in your advance.

Why does this work? As you are solely producing marines that cost 50 minerals and placing some buildings that cost 100 minerals, you are able to work with half the mineral income and still have constant production running.

When Terran pulls SCVs, it is strongest against zerg; however Mega Rax is also the hardest to hide from zerg.

In contrast with other races, Zerg is the only race that needs to decide whether he needs to spent his larvae on workers or on army units, as he is under pressure he will need to produce more army units at the cost of his workers. So, if you pull SCVs which gets your economy down, your opponent his economy will also be down because of the pressure that you apply on his production...

Solution 2:

Pulling your SCVs simply means bring them along and put them in the front of your army. If properly positioned, your opponent's zerglings will be attacking the SVCs (who can also do decent damage considering they are worker units) instead of attacking your marines, who can kill the zerglings off with minimal risk of even getting hit.

SVCs also allow you to build a bunker or two to help your push and again, make your marines live longer so they can do more damage.

I'm sure someone will come along and give a great answer that has a ton of detail, but since I don't play Terran I'm just going off what I've seen come at me and what I've seen casted.

Solution 3:

In this case, it means to take SCVs off mining to assist the marine army. The SCVs can:

  • Build/repair bunkers
  • Be used to soak up damage, especially if peeking up a ramp
  • Attack, if really going all-in
  • Block enemy units from moving