What hand tool do I need for this

[brianblock]

You need this buddy

JCB 3C 2 Ram Spanner

 

[rtbcomp]

Do you mean this?

http://www.ebay.co.uk/itm/JCB-3C-2-Ram-Spanner-/271265722036

How would the square pegs fit into the round holes?

 

[brianblock]

Didn't look too close at photo but a JCB 3c has rams just like yours with round holes

I bought a Britool one from eBay and just filed the corners off the square pins, it works a treat

 

[brianblock]

Britool 3152 2-4.3/4"