Crown SC4020-30:
Slow Travel

I have a SC4020-30 Serial 9a114182 that will only run on slow speed. I have checked the mast switch at the distribution panel and have 37 volt on TP7 and CA208-4 when mast is low. No voltage if the mast is raised passed the HGTS1 switch. Don't know what else to check.
  • Posted 27 Aug 2021 05:44
  • Discussion started by jordan_a
  • Missouri, United States
Showing items 1 - 6 of 6 results.
confirm that the speed does change above and below staging
just had another thought
it is common for the roller on the accelerator linkage to fall off
i assume you have checked your pot voltage
  • Posted 29 Aug 2021 09:25
  • Modified 10 Sep 2021 11:55 by poster
  • Reply by crownie
  • Victoria, Australia
I have had this problem multiple times. Most often it is height switch related. Have you followed the height switch cable all the way down to the connector, unplug it and use a paper clip to jumper it? I know you read power at dist board but I had one that had a bad spot in the cable and it was in the area where the cable would move when the mast was tilted. It would read good if the mast was in a spot where the cable was ok.

I also had one with a bad steer pot and the controller would slow down the motor speeds as well as several bad accel pots.
Posted 27 Aug 2021 11:18
Reply by 1CrownTech
Washington, United States

Excellent post from WA!
  • Posted 29 Aug 2021 07:57
  • Reply by KurtSchreiber
  • Washington, United States
I know at least five ways to set a machine on fire!
I am a professional, after all.
there should be at least one switch on the brake pedal, one will activate stop lights, other will reduce speed
check this switch on input and output of distribution board
  • Posted 28 Aug 2021 10:18
  • Reply by crownie
  • Victoria, Australia
I know there is a brake switch on the e-brake but don't know of any other brake switches. E-brake switch is working fine. This has been a problem for sometime I am not on this lift very often just was told about it.
  • Posted 27 Aug 2021 22:32
  • Reply by jordan_a
  • Missouri, United States
check your brake switch
is this a new fault or always been there as it could be in the tune
  • Posted 27 Aug 2021 16:51
  • Reply by crownie
  • Victoria, Australia
I have had this problem multiple times. Most often it is height switch related. Have you followed the height switch cable all the way down to the connector, unplug it and use a paper clip to jumper it? I know you read power at dist board but I had one that had a bad spot in the cable and it was in the area where the cable would move when the mast was tilted. It would read good if the mast was in a spot where the cable was ok.

I also had one with a bad steer pot and the controller would slow down the motor speeds as well as several bad accel pots.
  • Posted 27 Aug 2021 11:18
  • Reply by 1CrownTech
  • Washington, United States
1crowntechnician@gmail.com

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