Answer: Because Maxton developed a UT Compensation Circuit
Maxton developed a UT (Up Transition) Compensation Circuit for our valves back in 1998 to improve valve performance when operating under higher pressures and temperatures. This circuit increases the up leveling speed with load and temperature to maintain a more consistent flight time and eliminate long drawn out leveling times in the up direction. When leveling times increase in the up direction most of the oil is re-circulated back to the tank wasting horsepower and increasing operating temperatures unnecessarily. Maxton valves sense pressure change and increase leveling speed which helps shorten leveling times and reduce maximum operating temperatures.
Let’s look at two Maxton valves, one with the UT Compensation Circuit and one without showing two runs up and down at about 93°F. The Maxton valve (without UT Comp Circuit) has a longer leveling time and transition between the loaded and no load pressure condition which is shown in the trace and data highlighted in red below.
In the second performance trace (with UT Compensation Circuit) notice the red highlighted areas in the trace and data showing a faster leveling time and softer transition for better performance.
Benefits of Maxton UT Compensation Circuit
1-Less heat generated
2-Less energy consumption
3-Shorter flight times from floor to floor
4-Shorter leveling time with load
5-Better ride quality
Note: Points 1 & 2 equate to a “GREENER” elevator while 3 & 4 equate to more efficient traffic flow.
Another temperature related factor to manage involves oil viscosity. In the graph below the target operating temperature for AW 32 oil is between 100°F- 130°F. By maintaining this range of operating temperature the less viscosity change and therefore less valve performance change realized. However, there are more difficult cases to control temperature ranges and this is where Maxton valves provide additional help as shown previously above.