The Mobile Launcher is a transportable steel structure which provides the capability of moving the erected vehicle to the launch pad via the crawler transporter. The umbilical tower, permanently erected on the mobile launcher base, is a means of ready access to all important levels of the vehicle during assembly, checkout and servicing prior to launch. The intricate vehicle-to-ground interfaces are established and checked out within the protected environment of the Vertical Assembly Building (VAB) and then moved undisturbed aboard the mobile launcher to the launch pad.

Click image for a 1936x2440 pixel version of this image in a new window.
Adapted from Technical Information Summary, Apollo 11 (AS-506), p. 19 (p. 20 in the PDF), and Technical Information Summary, Apollo 10 (AS-505), p. 11 (p. 12 in the PDF)
Extraction, clean-up, and adaptation by heroicrelics.org.

1	S-IC Intertank (preflight). Provides LOX fill and drain. Arm may be reconnected to vehicle from LCC. Retract time 8 seconds. Reconnect time 5 minutes.
2	S-IC Forward (preflight). Provides pneumatic, electrical, and air-conditioning interfaces. Retracted at T-16.2 seconds. Retract time 8 seconds.
3	S-II Aft (preflight). Provides access to vehicle. Retracted prior to liftoff as required.
4	S-II Intermediate (inflight). Provides LH2 and LOX transfer, vent line, pneumatic, instrument cooling, electrical, and air-conditioning interface. Retract time 6.4 seconds.
5	S-II Forward (inflight). Provides GH2 vent, electrical, and pneumatic interfaces. Retract time 7.4 seconds.
6	S-IVB Aft [heroicrelics: corrected from "Forward" in original document] (inflight). Provides LH2 and LOX transfer, electrical, pneumatic, and air-conditioning interfaces. Retract time 7.7 seconds.
7	S-IVB Forward (inflight). Provides fuel tank vent, electrical, pneumatic, air-conditioning, and preflight conditioning interfaces. Retract time 8.4 seconds.
8	Service Module (inflight). Provides air-conditioning, vent line, coolant, electrical, and pneumatic interfaces. Retract time 9.0 seconds.
9	Command Module Access Arm (preflight). Provides access to spacecraft through environment chamber. Arm controlled from LCC. Retracted 12° park position until T-4 minutes.

Note: Preflight arms are retracted and locked against umbilical tower prior to launch.

Inflight arms retract at vehicle liftoff on command from service arm control switches (located in holddown arms).

Umbilical Tower

• Open Steel Structure
• Height: 380 ft
• Two high-speed elevators service 18 landings, from level "A" of the base to the 340 ft tower level
• Provides support for eight umbilical service arms, one access arm, 18 work and access platforms, distribution equipment for the propellant, pneumatic, electrical and instrumentation subsystems, other ground support equipment

Hammerhead Crane

• Launch position 90° CW from that shown below
• Load capacity 10 to 25 tons depending on extension of boom
• Can rotate 360° at 1 rpm

Launcher Base

• Two story steel structure
• Height: 25 ft
• Length: 160 ft
• Width: 135 ft
• Level "A" has 21 rooms
• Level "B" has 22 rooms

All text above taken from Technical Information Summary, Apollo 11 (AS-506), pages 18 & 19 (pages 19 & 20 in the PDF).