Did you know that cold weather can cause cab tilt cylinders to lock-up? In very cold temperatures, departments may have to use a different hydraulic fluid to avoid the problem.

NFPA 1901 requires that cab tilt cylinders be equipped with velocity fuses or other devices to prevent the cab from suddenly dropping if a hydraulic hose breaks. The fuses sense the force caused by the flow of hydraulic fluid as it passes through a small hole. If the force is too high, indicating a high flow caused by a broken line, the fuses will lock up the tilt cylinders.

In cold temperatures, the hydraulic fluid gets thicker and requires more force to make it flow. This increased force can cause the velocity fuses to shut and lock the cylinders. To avoid this problem, some manufacturers recommend a lower viscosity hydraulic fluid for temperatures below 0 degrees Fahrenheit. If your department experiences this problem, contact the apparatus manufacturer for recommendations.

This feature offers a variety of short tips and facts about apparatus maintenance and testing. Look for it every month. Submissions of 150 words or less are welcome from our readers, subject to editing. Send them to Senior Editor Chris Cavette at cavettes@ix.netcom.com.