and 23 1/2 feet raised. The base structure is 10
U-lock is inserted into a barrel groove to lock the
feet wide and 14 feet long; however, the upper
work platform extends the length of the whole
workstand to 21 feet when it's in the lowered
B-4A and B-5A Platforms
position. The work platform space is 4 feet by 4
feet square. The complete workstand weighs 1,900
The two most common maintenance platforms
are the B-4A and the B-5A, as shown in figures
3-16 and 3-17. Both workstands are movable,
The hydraulic system on the B-2 includes a
hydraulically operated, adjustable platforms with
hand pump, hydraulic lines, a reservoir, and a
ladders. They are mounted on free-swivel caster
hydraulic lift cylinder with a safety lock. The
wheel assemblies. Each wheel has a foot-lever
pump is located on the left-hand angle iron of the
actuated mechanical brake and a swivel lock
platform. Hydraulic lines lead from the pump to
the lift cylinder reservoir, which attaches to the
scissor section and platform structure. The work-
The steel-grated platforms are equipped with
stand is raised and lowered by using the pump and
safety rails on three sides, and there are handrails
the release valve, the same as a jack.
on the ladder. Both stands are equipped with lock-
ing pins that, when inserted through the top of
When the B-2 work platform is raised, the
the platform frame, lock the scissors. This
inner barrel of the hydraulic cylinder is exposed.
prevents the platform from collapsing in the event
This inner barrel has spaced grooves around it to
of hydraulic failure.
hold a safety barrel lock. Most of the models have
Both stands are raised by using a hydraulic
a barrel lock consisting of a ring with four spring
pump, which is located on the platform to the left
grips, which rides out on the piston. When the
ring is rotated, cams force the grips out free
of the barrel. When the ring is rotated farther,
the cams allow the grips to press against
the barrel and snap into one of the grooves.
The lock then prevents the cylinder piston from
collapsing in the event of hydraulic failure. You
may run across some models that have a U-shaped
bolt attached to the piston by a chain. This
Figure 3-17.-B-5A maintenance platform.
Figure 3-16.-B-4A maintenance platform.