The article below copied from the June 1965 issue of FIREMEN Magazine provides additional explanation on the use of two
piece Engine Companies.  It also gives insight on the uniqueness of P17 and W17 due to the special challenges and heavy fire load
in their first due area.
The Two Piece Engine Company goes way back in concept to the Chemical Hose Wagon, and Steamers of days gone by.  In the
Los Angeles Fire Department the concept has been maintained.  In the mid 60's they took on a new look, identified as a Pump and
Wagon, and in 1981 the Pump and Wagon was changed to reflect the Wagon as the primary Engine(11) and the Pump is designated
as the second Engine (211) and in stations with Heavy Duty Task Forces, the third Triple (311).

The basic concept utilized the main manpower on the Wagon ( Captain, Engineer and two Firefighters) laying lines, and positioning
themselves at the fire where equipment could be readily accessed for operations and the apparatus would supply as many hose lines
as needed, and a Engineer is assigned to the Pump who positions the Pump on the hydrant to supply the Wagon.  

In a cost saving measure in the early 50's, the Wagons tended to be Hi-Pressure Hose Wagons lacking the Volume capability of
their pumps.  The biggest disadvantage, would arise during brush fires, riots, and confligrations, where the Wagon couldn't be broken
down and used by itself and additional personnel man the Pump as independent units.  Thus the LAFD pushed for all Pumps and
Wagons to be Triple Combination Pumpers.  Even then, a few specialized Wagons would appear with Snorkels, Squrt, or
Telesqurts sometimes lacking even a tank, until later conversion and removal of the Snorkel/Telesqurt.

The earlier apparatus operating as Wagons would have manning of six personnel and in some cases large manifolds to supply large
quantities of water. Some of the earlier Pumps, had even two engines and two pumps to maximize their pumping capability.  
Something unique to the LAFD, even-though a lot of equipment would be dispatched, with a liberal compliment of personnel, the
apparatus would be utilized to capacity, using all discharges..  In contrast to the smaller departments that would respond fewer
apparatus, and lack the manpower to utilize the quantity of hose lines that their apparatus was made to utilize.

A significant tool used by the LAFD over the years was the Blake Four-way-valve, that allowed the Wagon to lay a supply line from
the hydrant into the fire, allowing utilization of the tank initially, and very quickly hydrant pressure, and once the Pump was in
position, the Engineer could hook is engine up to the blake and without interruption, switch the valve for Pump Pressure.  The LAFD
utilized 2-1/2", 3" with 2-1/2" couplings, and 3-1/2" hose well before common use of large diameter hose.  These hose lines would
be utilized in single supply line or parallel (dual) lines.

Another tool of the LAFD was use of transverse hose beds rather than high pressure hose reels.  The High Pressure Hose Wagons
initially stored the hose behind doors midship.  The doors were later removed, and new apparatus was ordered with midship
transverse hose beds, mounted above the cabinets, and three 1-1/2" gated discharges on each side, allowing one to three hose lines
to be pulled from either side, and extended according to need.

Special thanks to Christopher L. Arnold for providing this information and article below.