View Troubleshooting Procedures By Valve Model

Troubleshooting Procedures for UC1, UC1A, UC2, UC2AB44

 

Important Note

The information provided here is for use by skilled hydraulic elevator professionals. The possible problems and causes are listed in order of likelihood and ease of checking. Before disassembly of the valve, please make sure that you have powered down by turning off the main disconnect switch, and that the elevator is resting on the bumpers (zero system pressure). The first section of the guide deals with the “up: section, while the second deals with “down.”

It is important to use the following reference materials in conjunction with the troubleshooting procedures: Operating Sequence and Adjustment Procedure. If you need more assistance than the following pages supply, please contact our technical department by e-mail or call 1-775-782-1700.

Download PDF

You may download all procedures as PDF (Adobe Acrobat® Reader version 3.0 or later required), download the Maxton Mobile Mechanic APP or use the links below to view specific problems.

UP Section

 

Pump Runs,Car Does Not Move

  • Check valve for proper sizing in accord with adjustment instruction.
  • Make sure gate valves are open in system as required.
  • If car is resting on bumpers,make sure main down piston is not open by manually closing it with the D (Down speed)adjuster.Turn D (Down speed)adjuster in clockwise (CW)to stop,then back out counterclockwise (CCW)to it’s normal position (count number of turns in and out to avoid lengthy adjustment).
  • Turn US (Up Stop)adjuster in (CW)fully.
    (1)If car moves,check for proper voltage to coils.
    (2)If voltage is correct,remove US solenoid assembly.Visually inspect parts for foreign material and /or damage.Ball cage must operate freely within the solenoid tube.
    (3)If car does not move,repeat procedure with UT (Up Transition)adjuster and U solenoid assembly.
    -Remove BPS closure and piston.Examine piston ring for debris and /or damage,it must expand after it has been manually compressed. Clean or free if necessary. Check piston ring for ring groove wear. Make sure the large recycle spring grips the shoulder of the piston tightly.

Slow Up Acceleration

  • Turn UA (Up Acceleration)adjuster out (CCW).
  • Check belts and pulleys on pump and motor to make sure they
    are not slipping.
  • Remove control block and check up control fluid strainer for
    lint.If clogged,remove debris (in this case oil in the system
    must be filtered).
  • Check relief valve for proper setting.Refer to Adjustment Procedures.
  • Turn UT (Up Transition)and US (Up Stop)adjusters in (CW)fully. If car then accelerates properly,check both U and US solenoid assemblies
    for damage to seats, debris and free movement of ball cage.
  • Check motor for proper HP rating and line voltage for excessive voltage drop.

Up Acceleration Rough

  • Check jack packing and guide shoes for excessive tightness.
  • Check valve for proper sizing.

Up Speed Slow

  • Check belts and pulleys on pump and motor to make sure they are not slipping.
  • Check relief valve for proper setting.
  • Turn UT (Up Transition)adjuster in (CW). If this corrects the problem:
    (1)Check for proper coil voltage on up coils.
    (2)Check both U and US solenoid assemblies for damage to seats,debris and free movement of ball cage.
  • Check motor for proper HP rating and line voltage for excessive voltage drop.

Car Overshoots Floor

  • Turn the UT (Up Transition)adjuster out (CCW) more.
  • Remove the US solenoid assembly and check for foreign material and /or damage. Solenoid parts must operate freely within solenoid
    tube.
  • Check hatch slow down switch and stopping circuit to make sure there is no delay (one second lost means a three foot delay at 180 feet per minute).

Car Stalls or Leveling Speed Varies in Leveling Zone

  • Make sure the US (Up Stop)and U (Up)coils are connected in proper operating sequence.Refer to Adjustment Procedure.
  • Make sure LS (Leveling Speed)adjuster dot is referenced to the line between F and S.
  • Check relief valve for proper setting.
  • If car will not adjust using LS (Leveling Speed)adjuster,turn US (Up Stop)adjuster in (CW),then:
    (1)Check for proper coil voltage.
    (2)Remove US (Up Stop)solenoid assembly and check for debris and /or damage. Solenoid parts must operate freely within the solenoid tube.
    (3)Replace the solenoid seat.
  • Remove BPS closure and piston.Check piston ring for debris and /or damage,it must expand after it has been manually compressed.Clean or free the ring if necessary. Check the piston for ring groove wear.Make sure the large recycle spring grips the shoulder of the piston tightly.

Harsh Up Stop

  • Turn US (Up Stop)adjuster in (CW)for smoother stop.
  • Check that the pump continues to run after car has stopped for at least one second.As a check to determine adequate pump time,turn US (Up Stop) adjuster in (CW)all the way.Car should then level and stop above the floor.If not,there is not enough pump time.
  • Check jack and guide shoes for excessive tightness.If jack packing and guide shoes are in good condition,a soft stop will be accomplished by following the standard Adjustment Procedure.

DOWN Section

 

Car Will Not Lower

  • Check coil voltage.
  • Check line shut off valve and tank shut off valve.
  • Turn DS (Down Stop)adjuster in clockwise (CW)to stop.
  • Turn DA (Down Acceleration)adjuster out counterclockwise (CCW) more.
  • Turn DT (Down Transition)adjuster in (CW)slowly.If car will not lower,turn ML (Manual Lowering) screw out (CCW) all the way. If car lowers with ML screw open,first check for proper coil voltage.If voltage is correct,then check both D and DL solenoid assemblies for debris and /or damage. Solenoid parts must operate freely within the solenoid tube.
  • Replace the solenoid seat.
  • Remove Down closure and piston. Check piston ring for debris and /or damage,it must expand after is has been manually compressed.Clean
    or free the ring if necessary.Check piston ring for groove wear.
  • Check piston guide and seat for freedom of movement.

Slow Down Start

  • Turn DA (Down Acceleration)adjuster out (CCW).
  • Turn DS (Down Stop)adjuster in (CW).
  • Remove D solenoid assembly.Check for debris and /or damage. Ball cage must operate freely within solenoid tube.
  • Replace solenoid seats.
  • Check jack packing and guide shoes for any binding.

Harsh or Bouncy Start

  • Bleed air from jack.
  • Check for packing or guide shoe friction.

Fast Down Start

  • Turn DA (Down Acceleration)adjuster in (CW).

Car Comes Down in Leveling Speed Only

  • Check coil voltage to D (Down valve)solenoid.
  • Land car and remove D solenoid assembly.Check for debris and /or damage. Ball cage must operate freely within solenoid tube.
  • Replace solenoid seats.

Main Down Speed Too Slow

  • Make sure gate valves are open between valve and jack and between valve and tank.
  • Turn D (Down speed)adjuster out (CCW).
  • Replace solenoid seats.
  • Remove Down closure and piston.Check piston ring on Down piston for debris and /or damage,it must expand after it has been manually compressed.Check piston ring for groove wear. Install pressure gauge at “B” port.Check pressure during full down speed, no load and compare to flow chart. If there is any abnormal pressure drop, check for restriction in piping from valve to jack and from valve to tank.
  • Check flow capacities of pipe between valve and jack and between valve and tank (must not exceed 15 feet per second).

Down Transition Too Slow

  • Turn DT (Down Transition)adjuster out (CCW). This will necessitate readjusting the DA (Down Acceleration)adjustment.
  • Remove D solenoid assembly and check for debris and /or damage. Ball cage must operate freely within solenoid tube.
  • Replace solenoid seat.
  • Check slow down switch and relays for possible delay.
  • Check down control fluid strainer (under control block)assembly for lint.If clogged remove debris (in this case oil in the system should be filtered).

No Down Leveling Speed

  • Turn DA (Down Acceleration)adjuster out (CCW).
  • Turn ML (Manual Lowering)screw out (CCW).
  • If car lowers:
    (1)Check voltage to DL solenoid coil.
    (2)Remove DL solenoid assembly and check for debris and /or damage. Ball cage must operate freely within solenoid tube.
    (3)Replace solenoid seat.

Down Stop Too Smooth or Inaccurate

  • Turn DS (Down Stop)adjuster out (CCW). This will necessitate readjusting the DA (Down Acceleration)adjustment.
  • Remove DL solenoid assembly and check for debris and /or damage. Ball cage must operate freely within solenoid tube.
  • Check hatch switches and relays for possible delay.
  • Check down control fluid strainer assembly (under control block) for lint. If clogged remove debris (in this case oil in the system should be filtered).

Down Stop Too Rough

  • Turn DS (Down Stop)adjuster in (CW).
  • Check for tight jack packing or guide shoes.

Car Will Not Stop in Down Direction

  • Make sure coils are not energized.
  • Turn DT (Down Transition)adjuster out (CCW) fully.
  • Remove D solenoid assembly and check for debris and /or damage. Ball cage must operate freely within solenoid tube.
  • Replace solenoid ball cage.
  • Replace solenoid seat.
  • Remove valve closure and check piston guides to make sure they operate freely within their respective seats.
  • Check down control fluid strainer assembly (under control block)for lint. If clogged remove debris (in this case oil in the system
    should be filtered).

Car Drifts Slowly Down

  • Send car to upper floor.Open main power disconnect switch.
  • Close pit valve.If car still drifts the leak is in the jack assembly.
  • Back out seal nut on ML (Manual Lowering)screw one half turn.Turn ML screw in (CW) fully and re-tighten seal nut to insure good seat.
  • Turn DA (Down Acceleration)adjuster in clockwise (CW)fully. If leak stops,this indicates a leak at the down solenoids. Replace D and DL solenoid seats.Refer to Solenoid Kit #29292A.
  • To test leak at check valve:
    (1)Install gauge at “A” port and close gate valve between pump and tank.
    (2)Close bypass piston with BPS adjuster.
    (3)Turn UA (Up Acceleration)and UL (Up Leveling)adjusters in (CW) fully (count number of turns to avoid lengthy readjustment.
    (4)If pressure builds at “A” port,this indicates a leaking check valve.To dismantle the Check piston and guide assembly, insert an Allen wrench into the end of the assembly rod and remove the flex lock nut.Check the assembly rod and seal rings for debris and /or damage.
    (5)Examine Check valve seat for damage.
    (6)Remove snap ring holding check valve seat and examine seal ring under seat for damage and /or debris.
    (7)If leak is not indicated at Check valve,remove down closure and piston.Check seal ring and seat for debris and /or damage

Additional Procedures for UC2A (UC2)

 

Full Down Speed Too Slow

  • In examining flow charts,the down flow capacity of the UC2A (UC2)valve is 10 percent less than the UC1A (UC1)valve.

Car Drifts Down Slow

  • Before dismantling down section except when the problem is pinpointed to the control block,turn DSR (Down Speed Regulator)in (CW)fully. If this stops leak, examine the regulator poppit for debris and /or damage.

Down Speed Varies

  • Adjust with BA (Balance Adjustment)adjuster,turn in (CW)for slower and out (CCW) for faster.This adjustment must be made with a full load.

Troubleshooting Procedures for UC4, UC4M, UC4MRB44, UC3A, UC3AM

 

Important Note

The information provided here is for use by skilled hydraulic elevator professionals. The possible problems and causes are listed in order of likelihood and ease of checking. Before disassembly of the valve, please make sure that you have powered down by turning off the main disconnect switch, and that the elevator is resting on the bumpers (zero system pressure). The first section of the guide deals with the “up: section, while the second deals with “down.”

It is important to use the following reference materials in conjunction with the troubleshooting procedures: Operating Sequence and Adjustment Procedure. If you need more assistance than the following pages supply, please contact our technical department by e-mail or call 1-775-782-1700.

Download PDF

You may download all procedures as PDF (Adobe Acrobat® Reader version 3.0 or later required), download the Maxton Mobile Mechanic APP or use the links below to view specific problems.

UP Section

 

Pump Runs,Car Does Not Move

  • Check valve for proper sizing in accord with adjustment procedures.
  • Make sure gate valves are open in system as required.
  • Turn US (Up Stop)adjuster in clockwise (CW) until it stops.
    (1)If car moves,check for proper voltage to coils.
    (2)If voltage is correct,remove US solenoid assembly.Visually inspect parts for foreign material and /or damage. Ball cage must operate freely within the solenoid tube.
    (3)Replace solenoid seat.
    (4)Remove control plate and transfer line,check up control fluid strainer on transfer line for lint.If clogged remove debris (in this case oil in the system must be filtered).
  • If car does not move,remove valve closure. Examine bypass piston ring for damage.

Slow Up Acceleration

  • Turn UA (Up Acceleration)adjuster out counterclockwise (CCW).
  • Check belts and pulleys on pump and motor to make sure they are not slipping.
  • Remove control plate and check up control fluid strainer for lint,especially the bottom of strainer. If clogged,remove debris (in this case oil in the system must be filtered.
  • Remove valve closure.Examine bypass piston ring for damage.
  • Check relief valve for proper setting.Refer to adjustment procedures.
  • Turn UT (Up Transition)and US (Up Stop)adjusters in (CW)fully. If car then accelerates properly,check both U and US solenoid assemblies
    for damage to seats,debris and free movement of ball cage.
  • Check motor for proper HP rating and line voltage for excessive voltage drop.

Up Acceleration Rough

  • Check jack packing and guide shoes for excessive tightness.
  • Check valve for proper sizing.
  • Turn US (Up Stop)and UT (Up Transition)adjusters in (CW)fully (count the number of turns to avoid lengthy readjustment).
    (1)Register an up call,if problem continues replace BPS adjuster.
    (2)If car accelerates properly,or stalls in BPS sizing operation,either the US or UT ball check assembly must be replaced. Turn either US or UT adjuster out (CCW) one at a time and register an up call. When valve does not respond properly, replace respective ball check assembly or consult Maxton regarding replacement.

Up Speed Slow

  • Check belts and pulleys on pump and motor to make sure they are not slipping.
  • Check relief valve for proper setting.
  • Check for proper voltage on up coils
  • Check motor for proper HP rating and line voltage for excessive voltage drop.
  • Check both U and US solenoid for damage to seats,debris and free movement of ball cage.

Car Overshoots Floor

  • Turn the UT (Up Transition)adjuster out (CCW) more.
  • Remove the US solenoid assembly and check for foreign material and /or damage. Solenoid parts must operate freely within solenoid tube.
  • Check hatch slow down switch and stopping circuit to make sure there is no delay (one second lost means a three foot delay at 180 feet per minute).
  • Replace the BPS adjuster.

Car Stalls or Leveling Speed Varies in Leveling Zone

  • Make sure the US (Up Stop)and U (Up)coils are connected in proper operating sequence.Refer to Adjustment Procedure.
  • Make sure LS (Leveling Speed)adjuster dot is referenced to the line between F and S.
  • Check relief valve for proper setting.
  • If car will not adjust using LS (Leveling Speed)adjuster, turn US (Up Stop)adjuster in (CW), then:
    (1)Check for proper coil voltage.
    (2)Remove US (Up Stop)solenoid assembly and check for debris and /or damage. Solenoid parts must operate freely within the solenoid tube.
    (3)Replace the solenoid seat.
  • Remove the valve closure,examine bypass piston for damage.

Harsh Up Stop

  • Turn US (Up Stop)adjuster in (CW)for smoother stop.
  • Check that the pump continues to run after car has stopped for at least one second.As a check to determine adequate pump time, turn US (Up Stop)adjuster in (CW)fully.Car should then level and stop above the floor.If not,there is not enough pump time.
  • Check for tight packing or guide shoes.If jack packing and guide shoes are in good condition,a soft stop will be accomplished by following the standard Adjustment Procedures.

DOWN Section

 

Car Will Not Lower

  • Check coil voltage.
  • Check line shut off valve and tank shut off valve.
  • Turn DS (Down Stop)adjuster in clockwise (CW)to stop.
  • Turn DA (Down Acceleration)adjuster out counterclockwise (CCW) more.
  • Turn DT (Down Transition)adjuster in (CW)slowly.If car will not lower,turn ML (Manual Lowering)screw out (CCW) all the way. If car lowers with ML screw open,first check for proper coil voltage. If voltage is correct,then check both D and DL solenoid assemblies for debris and /or damage.Solenoid parts must operate freely within the solenoid tube.
  • Replace the solenoid seat.
  • Check down piston ring for damage
  • Check piston guide and seat for freedom of movement.

Slow Down Start

  • Turn DA (Down Acceleration)adjuster out (CCW).
  • Turn DS (Down Stop)adjuster in (CW).
  • Remove D solenoid assembly.Check for debris and /or damage.Ball
    cage must operate freely within solenoid tube.
  • Replace solenoid seats.
  • Check jack packing and guide shoes for any binding.

Harsh or Bouncy Start

  • Bleed air from jack.
  • Check for packing or guide shoe friction.

Fast Down Start

  • Turn DA (Down Acceleration)adjuster in (CW).

Car Comes Down in Leveling Speed Only

  • Check coil voltage to D (Down valve)solenoid.
  • Land car and remove D solenoid assembly.Check for debris and /or damage.Ball cage must operate freely within solenoid tube.
  • Replace solenoid seats.

Main Down Speed Too Slow

  • Make sure gate valves are open between valve and jack and between valve and tank.
  • Turn D (Down speed)adjuster out (CCW).
  • Replace solenoid seats.
  • Check down piston for damage.
  • Install pressure gauge at “B” port..Check pressure during full down speed and compare to flow chart. If there is any abnormal pressure drop,check for restriction in piping from valve to jack and from valve to tank.
  • Check flow capacities of pipe between valve and jack and between valve and tank.

Down Transition Too Slow

  • Turn DT (Down Transition)adjuster out (CCW).
  • Remove D solenoid assembly and check for debris and /or damage. Ball cage must operate freely within solenoid tube.
  • Replace solenoid seat.
  • Check slow down switch and relays for possible delay.
  • Check down control fluid strainer assembly for lint.If clogged remove debris (in this case oil in the system should be filtered).

No Down Leveling Speed

  • Turn DA (Down Acceleration)adjuster out (CCW).
  • Turn ML (Manual Lowering)screw out (CCW).
  • If car lowers:
    (1)Check voltage to DL solenoid coil.
    (2)Remove DL solenoid assembly and check for debris and /or damage. Ball cage must operate freely within solenoid tube.
    (3)Replace solenoid seat.
  • If car does not lower,remove valve closure,check down leveling spool and spring to make sure it is not sticking (or broken) and is assembled in proper order.

Down Stop Too Smooth or Inaccurate

  • Turn DS (Down Stop)adjuster out (CCW). This will necessitate readjusting the DA (Down Acceleration)adjustment.
  • Remove DL solenoid assembly and check for debris and /or damage. Ball cage must operate freely within solenoid tube.
  • Check hatch switches and relays for possible delay.
  • Check down control fluid strainer assembly (under control plate) for lint.If clogged remove debris (in this case oil in the system should be filtered).

Down Stop Too Rough

  • Turn DS (Down Stop)adjuster in (CW).
  • Check for tight jack packing or guide shoes.

Car Will Not Stop in Down Direction

  • Make sure coils are not energized.
  • Turn DT (Down Transition)adjuster out (CCW) fully.
  • Remove D solenoid assembly and check for debris and /or damage. Ball cage must operate freely within solenoid tube.
  • Replace solenoid ball cage.
  • Replace solenoid seat.
  • Remove valve closure and check piston guides to make sure they operate freely within their respective seats.
  • Check down control fluid strainer assembly (under control plate)for lint.If clogged remove debris (in this case oil in the system should be filtered).

Car Drifts Slowly Down

  • Send car to upper floor.Open main power disconnect switch.
  • Close pit valve.If car still drifts the leak is in the jack assembly.
  • Turn ML (Manual Lowering)screw out (CCW) and then turn in (CW)fully to insure a good seat.
  • Turn DA (Down Acceleration)adjuster in clockwise (CW)fully. If leak stops,this indicates a leak at the down solenoids. Replace D and DL solenoid seats. Refer to Solenoid Kit #292920.
  • If leak does not stop,this indicates a leak at the down guide seal.Remove Down /Check guide and examine seal on guide for damage and /or debris. Examine Down /Check seat.It must be free from nicks or scratches on the small internal radius.

Troubleshooting Procedures for EMV10

 

Important Note

The information provided here is for use by skilled hydraulic elevator professionals. The possible problems and causes are listed in order of likelihood and ease of checking. Before disassembly of the valve, please make sure that you have powered down by turning off the main disconnect switch, and that the elevator is resting on the bumpers (zero system pressure). The first section of the guide deals with the “up: section, while the second deals with “down.”

It is important to use the following reference materials in conjunction with the troubleshooting procedures: Operating Sequence and Adjustment Procedure. If you need more assistance than the following pages supply, please contact our technical department by e-mail or call 1-775-782-1700.

Download PDF

You may download all procedures as PDF (Adobe Acrobat® Reader version 3.0 or later required) or use the links below to view specific problems.

UP Section

 

Up Call Registered But No Up Travel

Cause Check Ref.
No power to VCB. Check VCB POWER indication. P7
Pump not running. Check pump disable circuit wiring. P5, 6

Pump Runs, Car Does Not Move

Cause Check Ref.
Line shut-off valve Check line shut-off valve open.
No UL Input signal to VCB. Verify UL input signal. P5, 6
No U and UL signals to VCB.
LED’s are off or dim.
Check U, UL signals at elevator controller.
Check for a broken or loose field interface cable from elevator controller to VCB.
Relief pressure set too low Check correct Relief pressure is set. P7
Clogged orifices, strainer. Check for oil contamination. P2
Up Compensator Valve not closing. Up Compensator Spool jammed. Up Compensator Spring broken.
Call Maxton for Assistance.

Up Acceleration Rough

Cause Check Ref.
Ride Quality setting. Change Ride Quality Setting. P7, 8
Sizing position incorrect. Call Maxton For Assistance.
Rail and / or packing friction. Check jack packing and guide shoes for excessive friction.

Up High Speed Slow

Cause Check Ref.
Low pump motor horsepower. Check motor horsepower rating.
Check line voltage.
Relief pressure set too low. Check relief pressure setting.
Note: If the Relief pressure is too low, the down high speed will be faster than normal.
P7
Pump output low. Check pump specification.
Check pump inlet strainer.
Incorrect Flow setting. Change Flow setting. P7, 8, 9
Incorrect MFC sizing position. Call Maxton For Assistance
Incorrect Jack size setting. Change Jack size setting P 7, 8, 9

Up Leveling Speed Slow / Stall

Cause Check Ref.
Incorrect Leveling Speed setting. Change Leveling Speed setting. P7, 8
Incorrect MFC sizing position. Call Maxton For Assistance
Incorrect Jack size setting. Change Jack size setting P7, 8, 9
Coil Sequence wrong Check controller for proper coil signal timing.
(i.e. U and UL dropping then UL re-energizing)

Car Overshoots Floor

Cause Check Ref.
Up Leveling Speed too fast. Change Up Leveling Speed setting. P7, 8
Ride Quality selection too soft. Change Ride Quality Setting. P7, 8
Up flow setting higher than actual pump output. Reset Flow setting. P7, 8, 9
Incorrect Jack size setting. Change Jack size setting. P7, 8, 9
U and/or UL signals turn off late. Check hoist way deceleration and stop switches.
Correct slowdown distance, if necessary.
P4, 7

Harsh Up Stop

Cause Check Ref.
Not enough pump time Increase pump time. The pump should continue to run for about one second after the car stops. P4

DOWN Section

 

Down Call Registered But No Down Travel

Cause Check Ref.
No Power to VCB. Check VCB POWER indication P7
Check VCB Fuse
Line shut-off valve Check line shut-off valve open.
Tripped pipe rupture valve Check and reset pipe rupture valve.
D or DL signals to VCB missing. Verify D, DL signals at elevator controller. P5, 6, 7
Check for a broken or loose field interface wire from elevator controller to VCB.
DV solenoid not energized Check the solenoid LED for power to the coil. Physically pick up the coil (quickly put it back) to feel the magnetic field at the coil. Replace coil, if necessary. P5, 6, 7
MFC malfunction Replace MFC, Call Maxton For Assistance

Car Slowly Creeps Down When Down Call Registered

Cause Check Ref.
DV Solenoid Check voltage to solenoid coil. P5, 6, 7
Check that DV solenoid is energized.
Replace solenoid coil, if necessary.
Check Orifice PN#876 Undersized Verify Orifice Dimension is .021, Call Maxton For Assistance
MFC malfunction Replace MFC, Call Maxton For Assistance

Down Leak

Cause Check Ref.
Leak at jack or line Close line shut-off valve. If car still drifts down,
Leak at DV solenoid Check solenoid seat P2
Leak at Main Check Valve Remove check seat and view for damage and/or debris, Call Maxton For Assistance
Manual Lowering Leaking Turn ML (Manual Lowering) screw out (CCW) and then turn in (CW) fully to insure a good seat.

Slow Start

Cause Check Ref.
Rail and packing friction Check jack packing and guide shoe tightness.
Ride Quality setting Change Ride Quality Setting P7, 8

Harsh or Bouncy Down Start

Cause Check Ref.
Air in hydraulic system Bleed air from jack.
Rail and / or packing friction Check jack packing and guide shoes for excessive friction.

Abrupt Down Start

Cause Check Ref.
Shuttle stuck Call Maxton For Assistance
Incorrect MFC sizing position Call Maxton For Assistance

Down High Speed Too Slow

Cause Check Ref.
Incorrect Flow setting Reset Flow setting. P7, 8, 9

Down Speed Not Regulated (Too Fast)

Cause Check Ref.
Shuttle stuck Make a full up run. Wait for 10 seconds, then make a down run. If problem repeats Call Maxton For Assistance
Clogged orifices or strainer Check for oil contamination. P2

Car Overshoots Floor

Cause Check Ref.
D and DL signal from elevator controller Check hoist way deceleration and stop switches. Adjust slowdown distance, if necessary. P4
Down Leveling Speed too fast Change Down Leveling Speed setting. P7, 8
Rate profile selection too soft Change Ride Quality setting. P7, 8

Down Leveling Slow or Stalled

Cause Check Ref.
Incorrect Down Leveling setting Change Down Leveling setting. P7, 8, 9
Incorrect Jack size setting Change Jack size setting.

Down Stop Too Soft or Hard

Cause Check Ref.
Rate profile selection Change Ride Quality setting. P7, 8, 9
Incorrect Jack size setting Change Jack size setting.

Miscellaneous

 

After a Run is Complete Car Moves Down 2-8″ During Pressure Relief Routine

Cause Check Ref.
Closing Orifice Clogged Remove closing orifice and check for debris P2
Check Piston not closed Call Maxton For Assistance

Erratic Up and Down Movement (Stop and Go)

Cause Check Ref.
Sensor unable to read encoder disk Remove sealant and check sensor cavity for oil. Clean with contact cleaner and dry with compressed air

Up High Speed Bogs Down Motor, Down Leak Present

Cause Check Ref.
Check piston Stuck Call Maxton For Assistance

Down High Speed Fluctuation, Ecessive Noise On Down Run

Cause Check Ref.
Pump Shuttle Stuck Call Maxton For Assistance

Troubleshooting Procedures for UC4HD, UC4MHD

 

Important Note

The information provided here is for use by skilled hydraulic elevator professionals. The possible problems and causes are listed in order of likelihood and ease of checking. Before disassembly of the valve, please make sure that you have powered down by turning off the main disconnect switch, and that the elevator is resting on the bumpers (zero system pressure). The first section of the guide deals with the “up: section, while the second deals with “down.”

It is important to use the following reference materials in conjunction with the troubleshooting procedures: Operating Sequence and Adjustment Procedure. If you need more assistance than the following pages supply, please contact our technical department by e-mail or call 1-775-782-1700.

Download PDF

You may download all procedures as PDF (Adobe Acrobat® Reader version 3.0 or later required) or use the links below to view specific problems.

UP Section

 

Up Call Registered But No Up Travel

Cause Check Ref.
No power to VCB. Check VCB for power to LCD Backlight P3
No UL Input signal to VCB. Verify UL input signal P4
No U and UL signals to VCB Check for a broken or loose field interface cable from elevator controller to VCB P4
Encoder, Up Motor, Up Home Sensor error See page 12, 13 for causes and fixes P12, 13
Up Strainer Clogged Clean Up Strainer P3

Pump runs, car does not move.

Cause Check Ref.
No UL Input signal to VCB. Verify UL input signal. P3
No U and UL signals to VCB. Check for U, UL signals at elevator controller
Check for a broken or loose field interface cable from elevator controller to VCB

Up Acceleration rough.

Cause Check Ref.
UA Setting Adjust UA Setting. P8
Initial setup incorrect Redo the learn mode P6
Rail and / or packing friction. Check jack packing and guide shoes for excessive friction.

Up high speed slow.

Cause Check Ref.
Low pump motor horsepower. Check motor horsepower rating. Check line voltage.
Relief pressure set too low. Check Relief pressure setting. P7
Pump output low. Check pump specification.
Check pump inlet strainer.

Up Leveling Speed slow

Cause Check Ref.
Slow Leveling Speed setting. Change Up Leveling Speed setting. P8

Car overshoots floor.

Cause Check Ref.
Up Leveling Speed too fast. Change Up Leveling Speed setting. P8
UT Setting to soft Change UT Setting P8
U and/or UL signals turn off late. Check hoist way deceleration and stop switches. Correct slowdown distance, if necessary. P3

Harsh Up Stop

Cause Check Ref.
Not enough pump time Increase pump time. The pump should continue to run for about one second after the car stops. P3

DOWN Section

 

Down call registered but no down travel.

Cause Check Ref.
No power to VCB. Check power to VCB (LCD backlight) P3
Check VCB Fuse
Line shut-off valve (cause ENCODER/SOLENOID error) Check line shut-off valve open. P12, 13
Tripped pipe rupture valve (cause ENC/SOL/OSV TRIP error) Check and reset pipe rupture valve.
DL or D and DL signals to VCB missing. Verify D, DL signals at elevator controller. P4
Check for a broken or loose field interface wire from elevator controller to VCB.
DV solenoid not energized (cause ENCODER/SOLENOID error) Check that DV solenoid is energized. P3
Home Sensor Error Check LCD for Home Sensor Error, flashing and alarm P12
Down Motor Error Check LCD for Down Motor Error, flashing and alarm

Down Leak

Cause Check Ref.
Leak at jack or line Close line shut-off valve. If car still drifts down check system for leaks
Leak at DV solenoid Check solenoid seat P3
Leak at down check piston Call Maxton For Assistance
Manual Lowering Leaking Turn ML (Manual Lowering) screw out (CCW) and then turn in (CW) fully to insure a good seat. P3

Slow start

Cause Check Ref.
Rail and packing friction Check jack packing and guide shoe tightness.
DA Setting Change DA Setting P8

Harsh or bouncy down start

Cause Check Ref.
Air in hydraulic system Bleed air from jack
Rail and / or packing friction Check jack packing and guide shoes for excessive friction

Down high speed slow or comes down at leveling speed

Cause Check Ref.
Incorrect Down Speed Setting Change Down Speed Setting P8
Encoder Error Check LCD Display for Encoder Error, flashing and alarm P12, 13

Down speed not regulated (too fast)

Cause Check Ref.
Incorrect Down Speed Setting Change Down Speed Setting P8

Car overshoots floor

Cause Check Ref.
D and/or DL signal from elevator controller Check hoist way deceleration and stop switches. Adjust slowdown distance, if necessary. P3
Down Leveling Speed too fast Change Down Leveling Speed setting. P8
DT Setting too slow Change DT Setting P8
Down Strainer Clogged Clean Down Strainer P3

Down leveling slow

Cause Check Ref.
Incorrect Down Leveling setting Change Down Leveling setting. P8

Down stop too soft or hard.

Cause Check Ref.
DS too soft Change DS Setting P8

Manual lowering speed too slow

Cause Check Ref.
MLS adjuster in (CW) too far Turn MLS our (CCW) to speed up P3

Manual lowering speed too fast

Cause Check Ref.
MLS adjuster in (CCW) too far Turn MLS our (CW) to slow down P3