Hi everyone.
Does anyone know what system of lubrication is used in pneumatic rock drills (Atlas Copco)? And what reduction in specific oil consumption means? Is it good or bad?
We switched from POE to mineral, got good results in pistons (low wear) and overall parts condition. But we also had reduction in oil consumption from 0.8 L/h to 0.6 L/h. Now customer is nervous about consumption.
Would be thankful if someone could explain the process.

I've tried to figure out this issue with an ExxonMobil engineer and Atlas Copco tech support. No answer, seems like this problem is too uncommon...

The Atlas Copco drills that Ive seen come with a Lincoln systems. Depending on the size of the drill they may use something as simple as a Quick Lube system. Reduction in lube is very common, it can be a good thing. The system needs to be adjusted in the field. The lube system is a tool, its up to you to calibrate it as each machine tends to be different. The type of oil, how the operator runs the machine, the type of drilling your doing all can have an effect. Precise lubrication using the system and the best lube can help your machine life last longer and stronger.

The funny thing is that operator didn't change the settings of lube system. So the system either automatically switched to lower consumption or the reason in the oil itself.
We changed ISO 68 POE on ISO 46 Mineral, maybe viscosity change induced recalibration.
I couldn't get any specifics on lube system from AC.

How long has the new mineral oil been in place? It may balance out as time goes on.

Viscosity changes can effect the usage on the lube system, it can with any pumping system. In my experience this is pretty common. However I would do whatever inspections you can to see if its being adequately lubed and adjust as necessary.

A simple system may work but you do not have the control of lube delivery. There is several ways to do this application but The injection point in the air circuit will also control if you have an intermittent lube delivery and/or continuous delivery........

The oil was working in the system for more than 1500 hours, and consumption stayed reduced compared to POE oil. In a sense lower visc oil (46) shoud be consumed more than higher one (68), but that is not the case apparently.
Sadly, i can't give more details as the drill is located in more than 2000 km from me.

If there was no change in the timer settings and the lube system is a positive displacemet circuit. The reduction in flow over the same time period means the system is not working as designed. The volume of oil displaced by the pump is the same for iso 46 and/or iso 68 oil.......