Ledge Hammers are obstacles that appear in Super Mario Galaxy 2. They are large black hammers with an orange stripe and are very fast, almost impossible to get past. However, they can be slowed down by using a time button. Ledge Hammers are rare obstacles, only appearing on one planet in Clockwork Ruins Galaxy. Six Ledge Hammers appear on the planet. Since they are hammers, their attack is crushing Mario or Luigi under their massive weight.
"Ledge Hammer" is a pun on the word "sledgehammer", but has the "s" taken out, and has a space.
The name "Ledge Hammer" probably came from the fact that the hammers are attached to ledges.