Fifth Wheel Power Landing Jack Leg Lubrication

A few years ago one of our Keystone Cougar fifth wheel landing legs completely failed. The leg no longer went up or down and couldn’t support any weight.  It ended up being a stripped collar nut in which the worm gear threads. We were on the road at the time, but I was able to order in replacement legs and do the repair myself.

I never figured out exactly why the nut failed, but one theory was a lack of sufficient lubrication. So, to help prevent failures and extend the life of the new landing legs I’ve decided to make sure they are well lubricated. This summer would be a good time to pull the legs, inspect and re-lube them.

Removing the Fifth Wheel Landing Jacks

Lucky for me removing the landing legs is relatively straightforward on my Cougar fifth wheel. First I have to remove the landing foot hardware and unbolt the inner extension legs spring locking mechanism.

Landing leg removed

Next, I unbolt the cross member that ties the lead and follow legs together. The lead landing leg is located on the driver side of the trailer and the follow leg on the passenger side. The only difference between the two is a longer shaft on the lead to accommodate the drive motor and gear box.

Follow leg and crossmember bolts

Then, I needed to remove two larger bolts that hold the landing leg to the fifth wheels inner frame. For the lead leg, an extra step is required. A small plastic collar gets removed and the gear box and drive motor slide off the landing legs drive shaft. Once all the hardware is unbolted, the landing legs simply slide out the top.

Removing motor and gear box

Lubing the Fifth Wheel Landing Legs

My primary concern is to get lubrication all over the long worm gear shaft that sits inside the leg. It’s like a giant screw. The solution I came up with is to take a 1 1/4 inch piece of plastic irrigation pipe and cut it in half lengthwise. Then coat the inside with bearing grease. The half pipe fits inside the leg and wraps around the worm gear allowing me to coat it well with grease.

Lubing the landing leg worm gear

Another location that needs attention is at the top of the landing leg where the input drive shaft and beveled gears are located. They are easily accessed by popping of a metal cap. I removed the old grease and pumped in a fresh batch packing it all around the gears and shaft.

Lubing the top bevel gears

To finish the lube job I took a can of silicone spray lubricant and wiped down the inner extension leg and sprayed some into the drive shaft bearings. While things were apart, it was also a good time to clean and lubricate the legs extension lock mechanism.

Landing leg lower spring lock mechanism

To test the leg for smooth operation and work the grease in I used my 1/2 cordless drill and ran the leg in and out several times. Before reinstalling, I carefully retracted the legs in as much as they would go, backed them off a slight amount and marked the legs inner portion with a red sharpie. The red line will give me a guideline for max retraction. Many times landing legs are damaged by over retracting.

I reinstalled the legs by reversing my steps and was good to go with a set of smooth operating front landing jacks.

Video Detailing Fifth Wheel Landing Leg Lubrication

See more Love Your RV! Fifth Wheel Maintenance Articles and Videos

How to lubricate fifth wheel trailer front landing jack legs by the Love Your RV blog - http://www.loveyourrv.com

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