Case Overview

GQZ, a professional bearing manufacturer and engineering partner, was approached by an international customer developing a mobile height-adjustable seat. The customer needed a low-cost, low-friction solution for the lifting sleeve of the seat's height adjustment mechanism, with an initial order of approximately 4,000 units and projected demand expected to more than triple from the following year.

Customer Challenge

The customer originally planned to install a bearing directly onto the square lifting tube. Specifically, they proposed welding one or four needle roller and cage assemblies onto a fixed square pipe, enabling the movable lifting sleeve to rise and fall flexibly with low friction and minimal clearance.

GQZ Engineering Analysis

After a thorough feasibility review, GQZ's engineering team identified critical technical issues with the customer's original proposal:

• Welding the cage to the fixed sleeve is not feasible. When needle rollers undergo pure rolling motion, the axis of the rolling elements simultaneously translates, just like a car wheel rolling on the ground where the axle moves forward or backward. If the axle does not move, the tire only slides against the ground without rolling, meaning friction is never converted from sliding to rolling.
• Leaving the cage unfixed is also not feasible. The internal dimensional accuracy of the fixed square pipe is relatively low, resulting in a large clearance between the needle roller and cage assembly, the fixed pipe and the movable pipe. The assembly may slide to the bottom of the fixed pipe under gravity and lose contact with the movable sleeve. Alternatively, when the movable sleeve descends, the assembly cannot continue moving downward, reproducing the same failure as the welded solution.

Solutions Recommended by GQZ

Option 1: Switch to a Round Pipe with Linear Ball Bearings

GQZ recommended replacing the square pipe with a round pipe and using linear ball bearings, which can be securely fixed onto the fixed circular tube. Because the balls move in a closed circulating path, they can generate translational motion while rolling even when the bearing housing is fixed.

Recommended models: KN 25 B-PP linear ball bearing (dimensions: d=25, D=40, C=58, C1=43.7) or LM25 linear ball bearing.

Option 2: Replace the Needle Roller and Cage Assembly with PTFE Patches

Attaching thin sheets made of PTFE or other low-friction materials onto the fixed square tube effectively reduces sliding friction while preserving the original structure.

Solution Comparison

Customer Value & Outcome

By applying deep bearing engineering expertise, GQZ helped the customer avoid a costly design flaw before mass production, delivering:

• Reliable, flexible lifting motion with minimized clearance
• Cost-effective solutions aligned with the customer's budget targets
• Scalable supply planning for the expected 3x+ order growth

Work with GQZ for Your Bearing Solutions

Every application is different, and choosing the right bearing technology can mean the difference between a smooth launch and a costly redesign. GQZ combines precision manufacturing with hands-on engineering expertise to help you validate your design, optimize performance and control total cost.

• Free engineering consultation: Send us your drawings and application details for a professional feasibility review.
• Customized solutions: From needle roller and cage assemblies to linear ball bearings and low-friction materials, we recommend and supply the right solution for your volume production.
• Fast response & reliable supply: Get timely quotations, samples and stable delivery to support your order growth.

Ready to optimize your next project?

Contact the GQZ engineering team today and let us help you turn your design challenge into a reliable, cost-effective production solution.