Marion (or others),
I was able to talk to a gentleman today who was the platoon leader that my Grandfather served under and he gave me some more information, but also led me to some more questions. I knew my grandfather was in the 157th Combat Engineer Battalion, Company C but I didn't know which Platoon or Squad. Today I found out that he was in Headquarters Platoon.
As I understand it, for the 157th, each of the three companies (A, B and C)had three Platoons and Headquarters Platoon. I was told the Headquarters Platoon consisted of approximately 38 men including Supply Sgt., cooks, Staff Sgt., Motor Sgt. Bull Dozer Operator, Air Compressor Operator, Radio Operator, Weapons Sgt. (what my Grandfather was), Etc.
I was told that the Weapons Sgt. was in charge of the machine guns (water cooled 30 caliber and 50 caliber on prime mover) as well as rocket launcher and other (?) weapons. He was not the front line guy with the weapons but was responsible to know where these weapons were at all times and keep them clean and in working order for the Company.
I tried searching for a breakdown such as this on the site and in my books but did not find anything like it. Do you have a Company breakdown that shows this information? Was this typical? If you do, do you know what other people would be in the Headquarters Platoon? Do you know of any other responsibilities for the weapons Sgt.?
This gentleman also told me about my Grandfather being "selected" while in Austria after the war to be one of two soldiers to go on a guided mountain goat hunt. I remember my Grandfather telling me that he and the other guy flipped a coin to see who got to shoot first and the other guy won, and got the goat! (My Grandfather is Frank Altman in the photo. This was not too far from Hitler's Eagles Nest)
The gentleman is in the process of writing his memoirs of his war years and of course I asked if I could get a copy when he is through. He said it was for his family and didn't know if he wanted to give it to others. I hope to be corresponding with him and exchanging photographs, so perhaps he will change his mind. At 92 he is sharp as a tack and was very nice to talk too!
Brian
Hi hopes this helps you further....
Most of the engineering regiments during WWII had TWO battalions, 1st and 2nd. Each battalion had three companies
1st Bn - A, B and C
2nd Bn - D, E and F
Companies are then broken into platoons, etc. Am attaching the WWII reference sheet on this.
Size of Army Units in WWII.pdf
Typically Headquarters unit was a company, not a platoon. A, B, C, D, E and F were called line companies. Then headquarters would come into play.
Bastard (or independent) engineering units such as the 157th and my dad's unit, the 540th, differed from the typical triangle setup of regular infantry units, for those units were based on THREE's. For example, the 34th Infantry Division had THREE regiments, and then each regiment had three battalions and so on. That was typical.
I saw the Size of Army Units in WWII when I was searching the site as well as your comments in another thread and didn't see anything like the platoon HQ. I had the gentleman go over it a few times on the phone as that was the first I had heard of anything like that. So, the 157th as you mentioned, did have the three companies (A,B and C) as well as a Headquarters Company, but it seems that they also had this platoon headquarters as well, perhaps one for each of the companies A, B and C?
I was able to find this gentleman in the After Action Reports, Rroster of Officers as 2nd Lt., and called Platoon Leader and Mess, Suply, Trans under Bn Prin Dy (which I assume means Battalion Principal Duty?). I guess the Mess, Suply, tran(sportation?) factors into the platoon HQ?
My list of questions for him is growing by the minute!
Thanks Marion
Here is an organization chart for an Engineer General Service Regiment found in Field Manual 5-5, Engineer Troops, page 150.
1st Battalion will be the same as 2nd Battalion ececpt 1st Battalion has companies A,B & C.
What a great find. Perfect. Thanks for posting that for him. 
Thanks SonofaMP, that'sgetting close. I am writing the gentleman with some additional questions so hopefully I will have a better understanding of it once I hear back from him too.
Brian
I found this one in the engineers field manual that I think resembles the 157th. 