One major difference between DC and AC motor is that the commutation process is absent in AC motor and present in DC motor. AC motor is suitable for large and industrial applications while DC motor is used in small and domestic applications.

Hey if we want to talk history, I have every Clarck , Redi Power and Carbon Pile digram if you desire.

Clark was the King at one time, Now Clark is the Hat, Not the Forklift!


Regards, Oldtimer,

Doc

Agreed Actronic is history, needs to be taught in Electric Forklift Evolution 101.


Doc

Hi,
I wonder if any of you guys can asist. I've got an Atlet CSH160 stacker in my shope that has a AC Drive motor. The motor generates hardly any torque. Just enough to move the machine when it's empty but not enough to move even the lightest load.
You can hear a quiet but high pitched whine when the motor is trying to drive but nothing else happens.
Dealer says re-calibrate but won;t tell me how. Can anyone offer advice? This AC stuff is new to me...

all this talk about the actronic is bringing back a head ache,errrrr,memories,like the electricar panel's.

Diesel,

Don't think Allis Chalmers was working on an AC drive system in the 1970's. They first introduced a tranistor based control in 1965 called PWM (pulse width modulation).

Around 1974 the PWM control was changed to the ACtronic control. It was still a transistor control using DC motors and controls. At that time they were using Allis Chalmers built drive and hydraulic motors.

Worked for the AC factory in there product development group from 1967 thru 1982

I would like to answer to liftdoctor about AC systems drawbacks:
- not all AC systems heat up faster than DC systems, depend on AC system technology. AC systems equipped with DCB power modules technology have better thermal performances than old DC system with traditional power modules ( see SME inverter system in the new PRO5 Doosan serie )
- power cut back is used to save motors during overload, but AC motors can reach higher temperatures than DC motor and they can ensure higher performances during high work
- based on cycle test, new lift trucks with DCB power modules technology can ensure from 10 to 15% lower power consuption compared with old DC systems

more information in grupposme or Doosan web site

The First company in the world to introduce (1991) AC technology in lift truck market with his customer FIAT, was SME group (www.grupposme.com) and then ZAPi copy this.

Did you know that Allis Chalmer was working on a ac drive prototype in the 1970's. The system was working but to big so they down sized it and it became a DC drive actronic system.

A-C shot themself in the foot for sure with their big cost reduction programs - dictated by Corporate (David C. Scott and company) and their first and last ever forklift 6.5% surcharge program in the mid 70's.

It looks like AC is hear to stay - DC technology is out the door. AC ain't new - most AC controllers come out of Europe where they have been well field tested - I call them 10's of thousands of prototypes for the US market.

If ya' ain't got it - you say it is bad & whatcha' got is good.

Here is a classic example of this.

Worked Allis Chalmers(A-C from 1967 to 1981. When the A-C PWM series (their silver bullet for the competition) was first introduced - A-C had 32% market share in class I. Beat the heck out of resistor & carbon pile controllers. Next year the rest of the lift truck folks installed GE 200 series SCR's controls(or something like that - CRS lite is settling in) - they all ganged up on them with tactics such as proprietary parts, GE parts everyone can work on them etc). A-C's market share, in class I went down to less than 10% the next year and to less than 5% (mainly due to reliability issues - competitors said I told you so) the next year.

Don't know what everybody else thinks but 3 guys in this forum always seem to talk good sense and I always read their comments with interest, well done guys you make the forum. They are: etharp, liftdoctor, and trainer. I think it has all been said and everyone seems to favour AC drive. In my humble opinion AC is best for Reach, Counterbalance and VNA. And SepEx is best for pallet jacks.
Only problem you will get with AC motors, is Encoder bearing failure. The motors are "Asynchronous" 3-phase motors. Which means the Inverter logic needs the feed back from the encoder in the form of 2 channels 90 deg out of phase to detect direction and speed. This allows the Inverter to synchronise rotor speed and frequency to maintain the motor at its most efficient. Think of it as the timing on an engine, as the RPM increase the vacuum advance moves the firing point more degrees before top dead centre. Ac motors run with a slip value that varies with speed a torque.........................Try disconnecting the encoder and test the result. The motor will not run or run very slowly with a high frequency vibration and the current readings will be through the roof. Don't run 'em for too long it could blow the inverter.
The bearings are tricky little buggers to replace and have to be fitted carefully to avoid damaging the encoder. I usually warm 'em up inside a plastic bag in warm water before fitting. Anybody got another solution? Some of my colleagues emery the seating to make it slip on easy, but I always think this could cause problems in the future!

Hi, We have 5 toyota´s 7FBEU18 and runs great with the AC drive, low maintenance, easy of service. Excelent units.
SOMEBODY hear something new about the new CLARK ECX with AC drive??

THank you

Trainer, no problem. I have yet to see how the AC motors hold up. If they hold up better, great!
The only high commutator bars I have ever seen from bulldozing are always on a 4 wheel sit down. The reaches, pallet jacks, tuggers, will spin the tires. The 3 wheel sit downs that have two drive motors just don't seem to raise a bar. I suppose it is because the current is distributed to two motors.

My co worker and I saw a new Raymond pallet jack that was AC drive. We both had the same thing on our mind: this is a sales gimmick in a pallet jack. The brushes in the drive motor are so easy to change in a pallet jack that the savings in maintenance of having the AC motor is insignificant. Most all DC drive trucks have seperately excited field windings now. The motors run cooler, and there are no forward and reverse contactors. There is also no need for a re-gen braking or field weakening contactor. There are seperate transistors in the controller for the field and armature windings. There is no fan on the controller running all the time like I see on most AC motor controllers.

This is an interesting discussion, but the guy who originally posted the question has not posted again. Did we answer his question?

I am not a salesperson....
My name is Trainer that could change...depends who is asking....
LOL

I was specifically talking about Class I, 3 and 4 wheel electrics....

Class II is another subject all together...

sorry if I had not specified class/model earlier

My fault... liftdoc

Trainer must be a Salesman for some barnd other than Crown and is trying to catch up. Your name wouldn't be Paul would it?

Crown pickers, transistor.
Crown 3 wheel sit downs, transistor.
Crown pallet jacks, transistor.
These are all seperately excited motors for drive.
Crown reach trucks: AC or DC. The price is the same. You pick AC or DC.
Crown turret truck: AC

The only Crowns that run EV100 is the RC and the FC. And my Raymaond friend says thier AC controllers won't handle a freezer environment.
Ha!

crown the king of electrics..(giggle)
use EV100

when will grandpa get some new teeth?

who knows..
some may say who cares....

Your statement about BT being a rebadged Jungheinrich is incorrect.

The low voltage jacks are still able to produce 100% torque at all RPMs.
The torque is a function of phase and so long as the phase is advanced far enough you get torque.

I can't argue about the low volts causing heat, however that'd be why companies like heinrich offer 48 volt jacks and 92-106 volt trucks.
Sadly NMHG is far far behind in this area, but we have recieved warnings about 96+ V units in the works.

In fact this is an area where ALL north american brands lag behind... but it's coming

BT's here in NA have been AC for a bunch of years, but they are simply rebadged heinrichs. I can attest to the speed, strength and durability of those reach trucks.

Abusing any electric truck will cause heat.
But I'd rather have a unit kick into thermal-cutback, then burn comms and brushes.

The Z series AC electrics from shyster are the fasteset, tourqeyest (sp?) units shyster has ever made. As long as you shut the 'economizer mode' off.(other wise they are real dogs :-) )

The shear number of wear items in a DC motored truck mean way more maintenance, period.

Every brand is AC or converting, so soon you won't have any choice.

It's just my humble opinion and I'm sorry if I offend.
I've worked on electric jacks, reaches, forklifts for 20 years, and the future IS ac.

It has been stated here that the AC motors have 100% torque 100% of the time, this is not very accurate, in fact the high voltage AC motors are great at producing torque but the low voltage motors have some serious issues. If you are bulldozing with AC motors you will have overheating problems especially in the lower voltages i.e. Power Jacks. The inverters will overheat and shut down. I would be very carefull when comparing AC technology to Advanced DC technology, I have witnessed two of the top Reach trucks one running on full AC and one running on full Advanced DC technology. The DC truck kicked the AC trucks butt. We used a police radar gun for speeds and the AC truck lost on just about everything. A company needs to be carefull before making this leap...Know the application and choose wisely.