Gym machines are often inaccurate with heart rate measurements and taking by hand is too slow as heart rate can drop very quickly once you stop.
Get a heart rate monitor with a chest strap and watch.
The machines with an automatic program based on heart rate don't know your range, they only go by a preprogrammed set of values that are don't fit everyone.
As I mentioned in my previous post, my max HR is 21 beats higher than predicted and that in normal for long terms athletes.
The 220-(current age) formula was intended to be used for the sedentary who are starting for the first time.
Also, sweat rate is not a good indicator of effort, too much individual variation and environmental factors can alter the perceived sweat rate.
"To give anything less than your best is to sacrifice the Gift."