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Often this problem raises its ugly head when an old dry power unit on the overshoot and re-level system is modernized with a submersible power unit. The intent is to speed up flight times in the up increasing passenger flows. The problem is short cuts are often taken that produce uncomfortable harsh stops making customers unhappy with the elevator ride.

In order to prevent harsh stops in this modernization example you must remember that the dry power unit operates differently than a submersible when stopping on the pump with overshoot and re-leveling to the floor. Basically, the dry pump unit has fly wheel spin that makes a slow stop while the submersible pump stops almost immediately.

So when replacing a dry unit with a submersible you must add hoistway slowdown switches, a controller upgrade to get the increased passenger flows and maintain the soft stop by stopping on the valve not the pump. If the costs to do this are prohibitive and the customer wants comfortable stops then replace the old dry unit with another dry unit and forgo the increased passenger flows.
Billy Shrum Technical Manager

All Maxton valves should be rebuilt at our factory with OEM parts by Maxton certified technicians using our Valve Exchange Program or Rebuild Program. There are companies out there that offer low cost rebuilds, but they don’t use Maxton OEM parts and they are not approved by Maxton. Don’t risk your reputation, product performance nor the potential safety of riders, it’s just not worth it. Read our Maxton Safety Bulletin Billy Shrum Technical Manager

All Maxton valves have three Ports to access either the system static pressure (B Port & S Port) or working/pump pressure (A Port). Why is this important you ask? Well the “S Port” is often overlooked, not used or not understood regarding functionality. Therefore, the “B Port” is then used for multiple access points through plumbing “T” fittings for gauges and low pressure switch attachment. This makes for a less professional look of plumbing and wiring. Maxton recommends using the “S Port” for the low pressure switch installation so all wiring can be cleanly tied together in one wire line while allowing direct or elbow connection of pressure gauge in the “B Port”. Billy Shrum Technical Manager

Maxton provides the optimal valve adjustment range in the adjustment procedures based on SafeTach readings for each Maxton valve. For example, the UC4 series DT (down transition) setting says:Register a down call and turn DT IN (CW) so that the car slows to provide 4 to 6 inches of stabilized down leveling.(Decel 0.04g-0.09g).The range in bold is the SafeTach decel reading you should see when the valve is properly adjusted. A softer ride will be on the low end while a firmer ride is on the higher end of this range.

This picture shows a decel rate that is outside the optimal range at 0.02g and needs adjustment (CCW).By using the SafeTach and adjusting to the readings you will increase your efficiency and the elevators performance in no time. Billy Shrum Technical Manager

When troubleshooting or adjusting a valve are you using the 20 minute rule?

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