CMP windshield throwout arm assemblies

[Charlie Down]

Thanks Jacques,
I think you are right about it being the wrong type, but interesting all the same. I don't think the 1533X2 had a vacuum supply to power the motors, I presume it was electric, but to be honest I have no idea! The photo shows a cable or tube feed to the motor.
On the operational vehicles it was removed anyway, but I just like to know what should be there, and it might help with what sort of bracket should be on the inside of the windscreen to mount the motor onto. Grant's photo shows a very simple bracket on a later CMP, but looking at the LRDG photo the bracket seems to be more complicated.

[Tony Smith]

Originally Posted by Charlie Down

I don't think the 1533X2 had a vacuum supply to power the motors, I presume it was electric, but to be honest I have no idea!

Certainly vacuum. There were a small number of car makers that provided electric wiper motors in the 40's, but usually on high value, low volume models. Certainly not on a Chev (or Ford) Truck, and not for a military model.

[Grant Bowker]

Originally Posted by Tony Smith

Certainly vacuum. There were a small number of car makers that provided electric wiper motors in the 40's, but usually on high value, low volume models. Certainly not on a Chev (or Ford) Truck, and not for a military model.

This is getting off topic, but didn't at least one Canadian jeep contract have electric wipers? I'll have to check parts lists but hopefully some of our jeep experts will be able to give a quick, definitive answer.
More later on what I believe would be a typical Canadian CMP (Chevrolet) wiper setup.

[Lynn Eades]

There are lots of variations in vacuum wipers, up into the later 50s (particularly British cars, often with a vacuum tank (with the hope that you might get at least one wipe as you climbed a hill) These were mostly mounted under the dash so had a separate control.
There were larger units (cylindrical bodies) in the M series trucks that were new (to the N.Z. Army) after the Vietnam war (70s) (e.g.M816- M818)
These were fitted in Wagner logstackers up to 2000. These big units, as I recall were pressure rather than vacuum. (still available?)

I have seen as thread on here talking about Canadian contract Jeeps with electric wipers.

Wipac is a common brand with British units appearing to have a "shield type cover (pointed at the bottom end) and U.S. ones having a cover shaped like a horse racing oval.(e.g. WWII WC Dodge. _ these were small units early on and were larger like the CMP ones later in the war)
The CMP ones like the Dodge ones had an operating lever (assist) as well as a push pull (on off knob) The CMP cover is more square with a rounded bottom.
I have a couple of them still sealed in their Ford V8 marked LV* CC15 17505. I do have a use for them.
I think they were extensively used as Tony said. I hope that helps a bit.

[Charlie Down]

Thanks for the info, learning every day!
So what generated the vacuum? Not come across anything on the various drawing and photo's that indicates a vacuum generator on the truck, so was a vacuum generated as a by-product of the engine to power the motor?
Tony, I hope it's a simple bracket, I'm not looking for complicated, I like simple. But more importantly I love accuracy and details! In the period photo with the arrow you can see what looks like a lip on the bracket. This could just be something in the background 'photo-bombing' the image. Looking at other components they are as simple as possible, so it's most likely a simple flat bar with 3 holes, just seeking confirmation.

[Tony Smith]

Vacuum is drawn from a threaded port in the Intake Manifold.

[Grant Bowker]

Originally Posted by Lynn Eades

There are lots of variations in vacuum wipers, up into the later 50s (particularly British cars, often with a vacuum tank (with the hope that you might get at least one wipe as you climbed a hill) These were mostly mounted under the dash so had a separate control.
There were larger units (cylindrical bodies) in the M series trucks that were new (to the N.Z. Army) after the Vietnam war (70s) (e.g.M816- M818)
These were fitted in Wagner logstackers up to 2000. These big units, as I recall were pressure rather than vacuum. (still available?)

When younger, I owned a M135CDN 2-1/2 ton truck. Being gasoline powered, the truck would have been capable of generating vacuum to run wipers but the truck definitely used compressed air to run the wipers, taken from the system that provided air pressure for brake boost, trailer braking and also had an outlet under the dash for a hose to inflate tires. I presume other trucks of the same vintage may have used similar components. One advantage of using air pressure is that if there is a small leak, there's no chance of drawing water into the engine (recall that they made a big thing of the early M series being sealed to run under water).

[Charlie Down]

At the moment it looks like a simple mounting bracket, although reading around it could have 4 mounting holes on early brackets and 2 on later ones. Phil Waterman photo illustrates this nicely
I'm also beginning to understand the variety of motors available for the MCP/CMP range with this Lynn Eades photo showing just a few of them.
So far though not matched any motor to last photo, which appears to have a block on the rear of the assembly at about 45 degrees. Or is that just an optical illusion?
Is it safe to assume they would be Trico motors?


http://www.mapleleafup.net/forums/sh...t=wiper+motors

[Lynn Eades]

Charlie, here is my opinion on your center photo.
Top two are CMP. and later U.S Mil. production.
Third down is U.S. manufacture. (eg. 42 Dodge 3/4 ton)
Bottom one is British.

This is just my opinion from what I have experienced. I could well be wrong.

I believe the big cylindrical ones can be converted from pressure to vacuum or vicky verco.
Also my comment about the hill was because when the throttle is closed you get the max . manifold vacuum and when the throttle is down (open) you have very little manifold vacuum, which results in the wipers slowing or stopping.

I have never seen the top one in your first photo, before now.

[Tony Smith]

The picture of the 4 wiper motors, the top one is the CMP/MCP type. This is a Trico unit known as the S Series. There are a variety of models within this series with different spindle lengths and mounting dimensions, but the operation of the mechanism is the same.

My understanding is that Cab 11/12 CMPs did not have the spacer bracket on the Windshield frame and used a short-spindle S 570 wiper. Cab 13 trucks which had the stand-off bracket mounted to the windshield frame (and therefore possibly the 1533 MCP) used either the S 609 or the S 548 with a longer spindle. Each of these came in a LH and RH version

[Tony Smith]

Originally Posted by Charlie Down

Grant's photo shows a very simple bracket on a later CMP, but looking at the LRDG photo the bracket seems to be more complicated.

I think they both look the same, as simple as it needs to be. What complexity do you see?