Hydraulics Case Study

Hydraulic Cylinder Cold-Start Sealing: Eliminating Spiral Failures at -25°C

NBRLT-NBRHydraulicsSpiral Failure

min temp

-25°C start

material rating

-40°C LT-NBR

warranty before

12 months

warranty after

24 months

Challenge

A mobile hydraulic cylinder builder had recurring spiral failures on NBR rod seals in cold-start conditions (-25°C).

Solution

We upgraded the material to a low-temperature NBR compound (LT-NBR) capable of -40°C, and adjusted groove width to reduce twist risk.

Result

Spiral failures were eliminated, and the customer expanded the product warranty from 1 year to 2 years.

Details

The customer's hydraulic cylinders were installed on construction equipment in northern climates. Cold-start temperatures of -25°C caused standard NBR rod seals to stiffen. When the cylinder extended under pressure, the stiff O-ring twisted in the gland, producing spiral failure marks.

We recommended a low-temperature NBR (LT-NBR) with improved low-temperature flexibility (TR10 of -42°C). This compound remained compliant at -25°C, allowing the seal to roll rather than twist during piston movement.

In addition to the material change, we reviewed the groove design. The original groove width was 2.0 mm for a 2.62 mm CS O-ring. We recommended increasing the groove width to 2.3 mm to reduce friction and allow freer rolling motion.

Field validation over two winter seasons confirmed zero spiral failures. The customer extended the standard product warranty from 12 months to 24 months and adopted LT-NBR as standard for all cold-climate cylinders.