Steering Question

[zlawson]

I recently purchased a Mack B- 61. I am new to the old macks but have always liked them so now I own one. I have found another truck with air assist steering and was wondering if anyone knows if it helps and how it works?

[vanscottbuilders]

Lawson,

Congratulations on the B-61 purchase, and welcome to our hobby.

Most B-61's had manual "Armstrong" steering.

The power assist systems that were offered both by the factory and as aftermarket parts were either

hydraulic systems or air powered assists.

The hydraulic systems were preferred for their smooth and seamless feeling. Some older Mack diesels do not have any provision for driving a hydraulic pump except by a coupler to the generator. Not the best of set-ups. But hydraulic power steering systems were pretty trouble free.

Air systems were a little more prone to problems, primarily related to leakage and blow-by in the systems.

The biggest complaints with air steering assist were capacity and "uneven feeling" complaints.

Capacity and recovery is definitely an issue. Constant steering input could result in a shortage of supply air that

temporarily reduces or eliminates the steering assist while the system "catches its' breath".

It is normally not an issue on the highway, rather air supply can be a problem when maneuvering a truck in close quarters. It is a temporary problem that self-corrects as the system is replenished with supply air. Leaks and blow-by might increase a capacity problem.

As for "uneven feel", some drivers didn't care for the feeling of the system as it waited a split second for action from the air cylinder. I believe that most of these type of issues could be corrected by adjustment, and proper system set-up.

Otherwise, air steering assist, I personally believe, was an enhancement to a truck of the 50's and 60's era.

It certainly would be "period correct" to fit air steering on your truck, and it would probably be an improvement.

As time went by - Hydraulic systems became more convenient and, ultimately, more dependable. Most, if not all, new trucks now use hydraulic power steering.

Good Luck with your project.

Paul Van Scott

[hatcity]

One problem, if going slow across uneven or terrain with lots of bumps. The wheel would suddenly turn WITH POWER. Learned not to put thumbs in way of spokes of steering wheel.

[blueknight0517@yahoo.com]

Lawson,

I have air asssist on my 1969 Mack R-600. When I rebuilt the truck, I found some problems as descirbed with the unit.

I contacted the manufacturer and replaced the worn parts and I am very pleased with the reuslts.

Air-O-Matic is the manufacturer. They are still in business and provide after markes power assist systems. I belive that the original system was designed for the Army and was installed in their trucks as an add on. If the system should fail, you still have manuel steering.

The system works off your air supply system. An air powered ram is attached to the tie rod and then anchored to the frame. The ram is powered in both directions. A valve system is installed in place of the drag link. When steering force is applied to the drag link via the steering wheel (either push or pull) the valve directs air to the approperate side of the ram while releasing air from the other side. force is applied to the tie rod and the assist is completed. There is a lag time and only shows up in tight quarters as previously mentioned. The system may not be as smooth as a hydrolic system but any assist is better then none.

I have had no problems with the system.

Jim

[Speed]

One of my ex-employers had an Autocar with air assist;the drivers all liked it a lot,but the neatest thing about it was that when driving in town or on the highway,they could throw a switch (looked like the power divider switch) and shut off the power assist. Most used it only at low speeds or in soft ground where the truck was heavy steering,and in the yard for jockeying trailers etc. The truck drove fine at anything over 20 mph,so it wasn't needed then. Good system,as I remember it...

Speed

[Rob]

One of my ex-employers had an Autocar with air assist;the drivers all liked it a lot,but the neatest thing about it was that when driving in town or on the highway,they could throw a switch (looked like the power divider switch) and shut off the power assist. Most used it only at low speeds or in soft ground where the truck was heavy steering,and in the yard for jockeying trailers etc. The truck drove fine at anything over 20 mph,so it wasn't needed then. Good system,as I remember it...

Speed

A lot of trucks had the toggle switch on the dash to shut the air to the torque link when on the road. My 74 RL has it and works great. I do prefer manual steering on the road but power sure is nice to jockey around with. It is not nearly as smooth in operation as a hydraulic system. As an example: If you are sitting still and start to turn the wheels, you initially hit a resistance and then just a short second later the effort to turn the wheels is reduced. This is from air pressure building on one side of the assist cylinder, and the other side exhausting through the torque valve. It takes time for the air to travel through the lines to the cylinder.

With a hydraulic assist, there is no exhaust and you are only displacing fluid so no delay.

Rob

[KAYLA]

HOW ABOUT SWITCHING FROM AIR ASSIST TO HYDRAULIC? WHAT IS NEEDED TO DO SO?

[mattb73lt]

5 hours ago, KAYLA said:

HOW ABOUT SWITCHING FROM AIR ASSIST TO HYDRAULIC? WHAT IS NEEDED TO DO SO?

The entire system. You can’t convert the Air-O-Matic to hydraulic. One add on system is from Garrison. Similar in nature to the Air-O-Matic, but hydraulic and has its own pump and reservoir. Another way is to replace the steering box with a power box. Sheppard was a supplier that made them and I’ve seen two sizes for the B model from them. I have the large unit Sheppard box from a B-61SX transplanted in my diesel powered B -42. I’m putting a Garrison assist unit in my B-73. My B-42 came with an Air-O -Magic unit, which I still have. It was fine but had the limitations spelled out in the earlier posts.

[Swishy]

Air O Matic takes a bit of getin use 2

U tend to oversteer until U familar with

 

2019FS54.bmp

[h67st]

Swish, I never thought of greasing the pins at each lock but it sure makes sense! I did that on my H, now I just need to get it driveable so I can try it.