I have a Sunbeam 19" Electric Lawnmower (made by Airgap Industries), Model No. 4419B-808, that worked really well until the electric switch / controller failed. The way the switch / controller worked is that squeezing the handle started the mower. Releasing it part way allowed the motor to slow by its own momentum. Releasing it all the way applied the brake and the mower blade stopped quickly. The motor head consists of four wires: Black, Red, Blue and White. I hope that someone can tell me how to wire this up to 115 volt house power to properly duplicate this operation. I realize that two heavy duty switches are probably involved and could probably figure out how to connect these two switches mechanically to duplicate the original switch / controller action.

Thanks for any help.

 

Take a look at this webpage to see if it helps.

 

Hello Mr. Pilot Dane:

I had previously checked out this webpage. Black & Decker electric mowers appear to have a DC motor and a rectifier module that converts AC to DC. The rectifier is apparently the "weak link". I have opened up the motor head of my Sunbeam and there is no rectifier so I suspect that it is an AC motor. As such it may be wired differently from mine. Also, the wire colors don't match up.

Here is some further information. The switch that failed is a "Schulte & Black" "Electro-systems" Type 710, 15 Amp 125 Volt. Unfortunately, when I disconnected the wires from the switch, I didn't do a complete job of writing down the connections. I tried to figure out the operation of the switch, but have been unsuccessful.

It's a great mower with lots of life left, if I can only recreate the switch action.

Thanks for your help. Maybe you or someone can steer me right.

 

Do you see any big resistors or anything that looks like a heater? I'm wondering if two wire power the motor when mowing then when you let go of the switch it becomes a generator and the power is dissipated in resistors or heaters to rapidly stop the blade.

Are you in a big enough city to have an AC motor repair shop? They might be able to tell you what each wire does. I'd hate to suggest just sending power to the black and red or black and white until you know what each does.

 

Hello Mr. Pilot Dane:

There are no big resistors or heaters when I took off the motor cover. All four wires seem to go into the motor head. I actually tried to run 115 volts AC into two of the wires. I didn't write down which. The result was that the motor ran for a few seconds and then blew the breaker, I believe. This was a long time ago, before I discovered this forum. The mower never blew the breaker when the switch was working normally.

I'm a little hesitant to just experiment like that. I'm hoping that someone who knows the design or who has a wiring diagram of the motor and switch can provide the pertinent information.

Thanks for the input and I'm open to any other ideas.

 

Hello:

Here are pictures of the mower with cover on and off, showing motor head.

 

Hello:

I did some follow-up; here is the information for anyone else who has this problem. The red and white wires are to the motor. The black and blue wires have something to do with the quick action brake. When I wired the motor red and white wires to 120 Volts AC, the motor spun up but it quickly blew the circuit breaker. Obviously, too much current. So I wired the motor and brake circuits in series: that is black 120 volts to black brake wire, blue brake wire to red motor wire and motor white wire to white "neutral" 120 volt AC return. Everything worked fine. However, when power is disconnected, the motor slows by its own momentum; no braking action.

I then broke the black 120 volt to black brake wire and inserted a switch. I intend to replace this switch with a 20 amp type because this is switching a large current.

Further follow-up would be to experiment with how to implement the brake action.

 

Hi MrMac7,
Did you solve your switch problem. I have almost the same lawnmower. It's a Sunbeam single blade electric mower. I am replacing brushes, and had to figure out the motor connections.
Also I would like to know where you bought your mower for spare parts, etc. Thanks.

Prelams

 

(This post is a bit speculative, based on photos of the switch wiring and some knowledge of induction motors. I don't own this mower, a friend several states away does, and I've not gotten a chance to physically touch the thing yet.)

This setup seems to use two motor windings, wired in series. When the switch is in "Run", the motor is connected to incoming power with the two windings seriesed together. In "Coast", the windings aren't connected to much of anything (one side is hooked to incoming power neutral, but that's it.) In "Off", the power is still disconnected, but the two windings are seriesed reversed and shorted out to itself - that makes the motor into a generator, driving basically a near-infinite load, so the motor stops turning very quickly. No mechanical brake needed.

Here's how the switch on a similar Sunbeam unit is wired:

The switch is a DPDT, Center Off - I'll number the pins thus:

1 2 3
4 5 6

The basic idea is that the two center terminals will be switched to either the adjacent terminals on one side or the other side, depending on the position of the switch toggle. The two sides of the switch are isolated from each other (in this case the white/black - red - blue side is isolated from the blue - white - black side.)

The two sides are:
1 Dark Blue; 2 White (to motor); 3 Black (from plug, i.e. incoming power);

4 White (from plug/power) AND Black (to motor); 5 Red (to motor); 6 Dark Blue AND Light Blue (to motor)

Thus, pins 1 and 6 are connected with a dark blue jumper wire.

How it works:

In "ON" mode, 2 and 3 are connected - that puts incoming hot on 3 to motor winding white - also, 5 and 6 (red and blue) are connected, which joins the two windings in series. The far side of the second winding (black wire) is permanently connected to the incoming neutral on switch pin 4. Thus power flows from the plug into motor white, out motor red, back into motor blue, and out motor black.

In "Coast" mode, switch in neutral position, nothing's connected by the switch to anything else. The motor just coasts, because the windings are disconnected from each other.

In "Off" mode, 1 and 2 are connected, hooking motor white to motor blue, and 4 and 5 are connected, hooking motor black to motor red. The two coils now fight against each other when the motor is turning, which takes the rotational energy of the motor and turns it into heat in the windings and wiring.

Here are photos of the switch in a similar Sunbeam mower (Model 3008, made by Toro.) It doesn't have the "Coast" feature, but that's just a matter of whether the switch is an ON-ON two-position type or an ON-OFF-ON three-position type. You can see the four motor leads in a cable, and a separate black and white from the incoming power plug. It's a bit weird that they chose to hook the incoming Neutral (white) to the motor black lead, and the incoming line (black) to the motor white. (Since it's AC and double-insulated, there's no difference in operation, it just gets on my engineer-nerves to see the colors hooked up backwards.)



In this photo the red circle shows where the wiring got a bit hot.



Hope this helps someone!