Denso starter 12v dc motor simple way to reverse rotation

I require to reverse rotation on a Land Rover starter motor reversing battery leads wont work I know the one way clutch will need to be reversed.

I have one motor goes the direction I require but another one has twice the power of that one but goes the wrong way this is the one would like to change rotation.

It's for a remote starter for my full size speed attempt flash steam engine.

A note for steam jet fans next weekend Graham Sykes Force of Nature steam jet motorcycle will be attempting to increase his 2022 speed at Melbourne Raceway near York

Hi,
You need to reverse either the brush connections OR the field connections but not both.
It's normally easier to reverse the brushes.

Robert.

Edited By Robert Atkinson 2 on 08/04/2023 14:03:04

Assuming that this Denso is the same generic motor [big assumption?] then there is a sprag clutch in the drive

… see about ten minutes into the video:

I'm very out of date with starters but the Lucas motors I've opened up in the past were series wound so swapping the field supply will mean, I think, altering the internal coil connections so not entirely straightforward, especially as the conductors are very heavy and stiff.

If it's designed for one direction operation, the brushes might be a bit offset (don't ask me why!) and so it won't run as well in the other direction. Might still be enough of course

Exactly what model starter is it? A photo of the brush gear would help too. It might require slots cut in the cover to allow external links to cross the connections. I have done this before on this type of motor. I did it twice, undoing once, on the back-up hydraulic pump motor used on Thrust SSC. First because the hydraulic designer didn't check the rototion of the parts he bought. It was then undone because the gear type pump could have it's ports reversed instead and then redone because he forgot that the pressure regulation by-pass valve was built in and had to be on the output.....
The brush offset mentioned by Duncan is to compensate for armature reaction wher the rotating fieldcaused by armature current distorts the fixed field effectively moving the optimum brush position. Might cause a bit of sparking at the brushes. You will have to try it and see.

Robert.

Clive is correct starter motor are series wound motors. I altered a Lucas starter motor several years ago when making a 12 volt battery powered loco. The carcass was connected to earth, so I went inside and brought out an extra terminal, which permitted forward and reverse running. Also some more modern starter motors have brushes which are off set, with a trailing edge so if you reverse you may find you finish up with lots of broken brushes My motor wasn't a pre engaged type as I sure Landrover will be. John

Did this with an old Lucas starter 40 years ago to make an electric winch - it worked. Series wound so brought out an extra terminal,and I seem to thing 4 solenoids. Noel.

I think you will not (easily) reverse the bendix. The pinion teeth are likely chamfered, for easier engagement with the flywheel ring gear.

Here is a more sophisticated one from USA there are many simpler designs.

Am thinking of converting my more powerful starter to reduction gear drive that would solve the rotation direction if the less powerful starter does not give enough torque to start my engine

https://www.facebook.com/cycledragracing/videos/a-new-way-to-start-your-motorcycle/493913058433405/

I remember wiring a full-wave diode bridge rectifier onto an electric motor so that the field winding was always the same polarity even when the voltage into the motor was swapped, making it easily reversible.

However, as others have warned; the brushes in some motors might not like the commutator running backwards !

Edited By John Doe 2 on 09/04/2023 09:48:49

What are you actually starting? I guess an IC engine driving a feed pump?
Depending on skill sets, parts availablity, design requirements and compromises gearing or using a different starter may be better options. Typically external starters don't need the engagement solenoid for example.

Robert.

It's a full size version of my 129.33 mph record model flash steamer a lot steam pressure on top of inlet valve

Second hand car starter motors certainly have a price advantage, but another possibility might be an electric winch motor, which is designed to run in either direction.

Bill

Taking the easy way out, if possible.

Could you mount the starter motor, so that it points the other way?

In that way the motor rquires no modification, other than to the orientation.

Howard