Electric Power Assist Steering (EPAS)

smt-flxible · February 25, 2018, 12:13:28 PM

Greetings, Newbie here. We own a 1949 Flxible bus and i am wanting to add power steering. Does anyone have any experience with the new ELECTRIC POWER ASSIST Systems in a vintage BUS application? I see these are commonly being used in streetrod applications and light trucks but i have only located one vendor ( in the UK) that state they have an EPAS unit rated for 5-7 ton vehicles. I am looking for pros and cons. I would love to talk with someone who has installed one of these. Here is a link to Easy Steer http://www.easysteer.co.uk/ This is the kit i am considering. Go to the DIY tab- then B Series Kit. I have not had much luck getting any info or specs other than what is posted on their website.

Thanks in advance, Jerry
jerry.ashley28694@gmail.com

Lee Bradley · February 25, 2018, 01:30:00 PM

I have a factory unit on one of my cars and I have never liked it. It is not a smooth as hydraulic. They might have improved them since '05.

HB of CJ · February 25, 2018, 01:39:37 PM

Respectfully ...

Welcome to this Excellent Bus Conversion Forum. I am located on the NW-W Pacific Coast of the USA. Years ago in about 1970 I drove an old big school bus that had AIR powered power assist steering. It worked great on the open road. Also worked fine in city driving.

Where it did not work so great was in tight back and forth heavy steering applications like downtown or tight school event bus parking. The heavy use of AIR quickly ran down the bus brake air pressure. Many times I had to just stop and sit and rebuild up air pressure.

We also experienced this in the Pacific Northwest USA with forest logging applications. Air power assist was tried and it does work mostly. But there were times when I had to re air up the air pressure sitting still before I could steer again spotting the big logging truck.

Hot rod and other light vehicle weight electric assist works probably because the usage and power required to operate the system is doable and mountable in that light weight vehicle platform? How much electrical power would it take in a much heavier bus?

Plus the probably fact hot rods and cars have a 12VDC system? Not 24VDC? Plus the wiring requirements would be much less. How much load would such an electrically assisted power assist system absorb or require in a Bus Conversion? Be a fun study.

I dunno. (I do not know.) Might be a considerable amount. Batteries? Alternator? Wiring or cable size?

Respectfully ...

PS: In the summer of 1970 I got to drive a 1949 Flexible highway coach. Had all the small windows in the low roof. Fun to drive. Long ago, far away.

TomC · February 26, 2018, 07:15:25 AM

When I bought my bus, it had air assist steering. Fine in town going stop light to stop light-like the bus was designed for. But get on the highway, and it was a lot of work keeping the bus straight-because of the natural sloppiness in the steering from the air control valve. And on a curvy highway was a lot of work (steering was 8 turns lock to lock). Maneuvering, was hard too with running out of air.
When I found a complete steering system from another AMGeneral, I bought it. Granted it ultimately was about $2,500 to switch, but man what a difference. Had 3.5 turns lock to lock and finger tip maneuverability when backing. Just install a normal Sheppard type steering. Is your steering box mounted on the axle or on the frame? Good Luck, TomC

PP · February 26, 2018, 08:58:45 AM

I thought EPAS steering is what all the new ATVs are using for power steering. Has nothing to do with air. Runs off battery. I also heard that some have adapted the EPAS to street rods and such, but have not heard of anything as large as a bus using it. Got me curious now...
Will

TomC · February 27, 2018, 08:04:27 AM

Power steering pump on a bus pulls 5-10hp when turning. I don't think a battery powered electric would keep up. Good Luck, TomC

Jeremy · February 27, 2018, 12:45:56 PM

There's a 2015 article here discussing the technical merits and limitations of electric and electric-hydraulic power steering systems on heavy goods vehicles - it does sound like the electrical supply is the main limiting factor when the systems are installed on larger and heavier vehicles (eg, specifically mentions the system drawing a current of 130A when in use on a 10-ton vehicle, and still not being able to deliver the power required):

http://articles.sae.org/14136/

Jeremy

HB of CJ · February 27, 2018, 01:50:47 PM

Respectfully ...

Yep ... it sounds like an electric assist power steering installation might be tricky. Difficult. Imagine the power requirement being close to that of a starter turning the engine?

If you could install the unit and run properly sized very heavy cable to and from the assist unit it might work fine? The problem is the draw down upon the charging system.

Would the system handle it? If sucking power directly from the batteries it might work. The alternator would have to keep up. Heavy slow turning might overwhelm the system?

I do not know. Dunno. Or ... could a big battery(s) just give out that necessary power and easily be slowly recharged by the alternator? What about night time heavy turning?

Would everything else in the electrical system be able to keep up? Ultimate situation. Night time. A/C running. Interior lighting. Tight lengthy steering? All to be considered.

Respectfully. Welcome to this Excellent Bus Conversion Forum.

smt-flxible · March 02, 2018, 03:35:04 PM

Greetings, Thanks for your replies and comments to date. Please allow me to respond to a few of the comments. 1st our vintage (1949) bus is 12 volt positive ground not 24 volt. The Easy Steer System is not Hydro over electric but rather total electric. If the system fails it reverts to the same steering w/o the Easy steering. I plan to contact Micheal at Easy Steer to discuss the wiring requirements and the voltage/ amp draws . I understand and share that concern. Thanks Again! I will keep you posted. Jerry