Whatever happened to landing gear with rollers?

Used to call them landing gear dolly wheels. You always had to hook your airlines up first,and charge your trailer brakes,before hooking to the trailer. Otherwise you'd be chasing the trailer around in reverse,trying to get it up on the fifth wheel. 99% of those old trailers didn't have maxis,and the air would leak off and they'd just roll around when you tried to hook up.

 

With this industry going to a drop and hook system, more and more trailers are sitting loaded. I would imagine one problem with this style of landing gear would be a tendency for it sink in the soft ground much easier than a landing gear with a large plate at the bottom.

Forgive me, I can't understand your point about "chasing the trailer". I'm not a mechanic but I was under the impression a trailer spring brakes did NOT need to be "charged" to hold while backing under it. Also if the driver is correctly backing under the 5th-wheel is raising the landing gear off the ground a bit as it goes back.

 

Older trailers didn't have spring brakes.

 

No spring brakes on old trailers, just service pots. You "dynamited" them. There's a special relay valve on those old trailers called a relay-emergency valve. Its purpose is to put full trailer reservoir pressure to the service brakes when pressure is exhausted from the trailer supply line.

 

Red, Yellow and Blue buttons.

 

You don't need the blue button to pull an old trailer without spring brakes though.

 

I know. Just something else that many have never seen.

 

I often wonder if pole-type log trailers were exempt from that ruling. I've seen some built up until the mid 90's with just service pots on every axle.