About half the gyms I've been to use lbs over kilograms. The problem worsens when machines list plates as 10, 20 , 30 etc with no indication of what that 10 or 20 is measured in. There have been several gyms where I've noticed machines being in a different measurement to kilograms, whether it's lbs or simply a level indication.
Does your machine explicitly say kilograms? The only reason I ask is because the weight your doing is extremely high, all of the biggest guys in the gym only just manage to come close to that. You must have a massive back and biceps to pull it down to your chest.
I guarentee it's in KG. Heres why from what your talking about earlier hanging from it etc. I weigh 13 stone which is like 83 kilos. If I jam it on 124 like I usually do I can hang from it without touching the ground etc. But the machines are def in kilos.