MEEB: Vertical Transportation: Hole-less and Roped Hydraulic Elevators

MEEB: Vertical Transportation: Hole-less and Roped Hydraulic Elevators

Hole-less Hydraulic Elevators

Used where drilling a plunger hole presents difficulties.

Uses a telescoping plunger, single jack or dual jack (used more often) mounted to sides of car

require more maintenance, but easier to get to

dual jack, creates less smooth ride causing a degree of jerk.

Roped Hydraulic Elevators

Simpler than telescoping

uses only a single moving jack section compared to two or three.

by using 2:1 roping meaning car travels twice as far as the piston

Accomplished by passing rope over a pulley in the piston crosshead.

One end of rope attached to fixed point in pit below car, other end attached to base of car

Piston lifts the crosshead and in turn lifts the car

Most common choice for low rise, light to medium duty hydraulic.

Roped, so equipped with slack rope safety in addition to other safeties.

MEEB: Vertical Transportation: Hydraulic Plunger Type Elevators - Plunger Type

MEEB: Vertical Transportation: Hydraulic Elevators - Plunger Type

Raised and lowered by means of movable rod (plunger) rigidly fixed to the bottom of the elevator car.

More inexpensive than Traction = No cables, drums, traction motors, elaborate controllers, safety devices or penthouse equipment required

Seed & rise = low speed - 200 fpm & low-rise - up to 65 ft

Hydraulic oil used, powered by an oil pump.

No overhead machine room required (a big plus)

Additional advantages over traction units:

Load is carried by ground rather than structure at top of shaft

Smaller hoistway due to absence of counterweight and its guide rails

cars lower manually by operation of oil valves (good if control equip. or power fails)

No limit to load that can be lifted

Inherent disadvantages

- operating expense

- not counterweight creates necessity of large motor to drive oil pump and all energy is lost in heat.

- limited to low rise, low speed applications, four story max.

- ride quality inferior to traction

- temp of pump and oil storage tank must be controlled to keep oil viscosity at acceptable levels

- high inrush of current taken by pump each time ti travels up requires a "stiff" power supply to avoid line voltage fluctuations.

- Pump, motor and piping can be noisy, mitigation by locating pump mechanism up to fifty feet from the elevator shaft

Plunger type have been used less due to oil seepage into the ground, Hole-less and roped Hydraulics have come into more common use in response.