How to Fix Intermittent Drive Problems on Nobles SS5 & Tennant T5e Scrubbers
Have you ever been mid-clean with your Nobles SS5 or Tennant T5 floor scrubber, only for the machine’s propel function to suddenly drop out or stop working altogether?
When your machine loses drive in forward or reverse—especially when set to variable speed—it can bring operations to a complete halt. At Robey’s PowerKleen, we know how important it is to keep your equipment running smoothly without unnecessary downtime.
Before assuming you need an expensive drive motor replacement, check one simple, commonly overlooked component: the trigger assembly switches..
🎬 WATCH: Quick Video Walkthrough
In this short video guide from Robey’s Powerkleen, we break down the Tennant T5 / Nobles SS5 trigger assembly and show you step-by-step how to clean and service the internal contacts.
The Common Cause: Trigger Switch Assembly Issues
Inside the left and right handle trigger assemblies, there is a small contact switch operated by a mechanical cam. When you pull the trigger, the cam depresses a small button on the switch to signal the machine to propel.
Over time, two main issues tend to occur:
Loose or Misaligned Cam/Trigger: The mounting nut on the switch can back off, making the trigger loose. When this happens, the cam won’t fully depress the switch button—even when you pull hard on the handle.
Contact Corrosion & Char Marks: Because this switch operates in a low-voltage, low-current application (1 to 5 volts with very low amperage), even minor galvanic corrosion, char marks, or oxidation on the internal brass bus bar can disrupt the electrical signal. This causes intermittent dropouts where the drive cuts out while operating or fails to respond until you pump the trigger multiple times.
How to Diagnose the Issue
Test both triggers: Try switching from the right handle trigger to the left (or vice versa).
Pump the trigger: Rapidly press and release the trigger. If the drive suddenly kicks back in after pumping it a few times, a dirty or misaligned contact switch is almost certainly the culprit.
Step-by-Step DIY Repair Guide
You can often service and restore these switches in just 2 to 3 minutes using standard tools!
1. Inspect the Housing & Cam
Remove the trigger housing and check if the mounting nut is tight. Ensure the trigger cam depresses the red switch button fully when pulled.
2. Disassemble the Small Contact Switch
Locate the four metal tabs (“ears”) on the side of the switch housing. Gently pry or loosen these tabs with a small flathead screwdriver to open the switch casing.
3. Clean the Internal Contacts
Once opened, inspect the small brass bus bar and internal contact pads. Look for black char marks, discoloration, or corrosion.
Use a small wire brush along with contact cleaner or carb cleaner to thoroughly scrub the pads.
Clean until you see bright, shiny brass metal.
4. Adjust and Reassemble
If the brass plate inside looks bent or flattened, carefully bend it back up so it makes solid contact.
Reassemble the switch housing.
Use needle-nose pliers to crimp the metal tabs tightly back into place.
Repair vs. Replacement Cost
DIY Service: Free! Cleaning the existing switch takes under 5 minutes.
Replacement Switch: If the switch is bent beyond repair or physically broken, a replacement switch costs around $7, while a full switch assembly is roughly $50.
Need Expert Help or Equipment Parts?
At Robey’s PowerKleen, we are committed to helping you maintain your cleaning machinery with expert advice, quality parts, and professional service.
If you’re having trouble troubleshooting your Nobles or Tennant equipment, reach out to our service team today!
