§3088. Screw Type Elevators.

(a) Hoistways, Hoistway Enclosures and Related Construction. Hoistway, hoistway enclosures and related construction shall conform to the requirements of Article 7, except as the requirements for elevators with screw type hoisting means are modified by the following:

(1) Section 3010. (Hoistway Enclosures) Safe access to the hoist machines located on the car or in the pit shall be provided from the machine room at the lowest landing or pit level. The access door shall be electrically interlocked to prevent operation of the car when the door is not closed and locked.

(2) Section 3011. (Machine Room)

(A) Hoist motors, rotors, brakes and reduction gears may be located on the car top or in the pit provided.

1. Hoist machines located on the car top are permanently enclosed so they are inaccessible from the car top.

2. Access to drive machines mounted on the car or located in the pit is from the bottom level machine room only. An enclosure shall separate the drive unit on the car or in the pit from the machine room. Access doors shall comply with the requirements of Section 3088(a)(1).

(B) Screw fastenings, car lowering mechanisms and car overspeed governors may be housed in a removable enclosure secured against unauthorized access.

(C) Where the drive unit of a screw type elevator is located in the elevator pit, a permanent means shall be provided in the pit to support the car and platform during repairs or adjustments of the unit. Clear headroom under the platform shall be not less than 7'0" when the elevator is landed on the supports.

(3) Section 3017. (Top and bottom runbys and clearances)

(A) Elevator top and bottom clearances and runbys shall comply with Section 3017 for elevators with electric drive motors and Section 3054 for elevators with hydraulic drive motors.

(B) The bottom runby required by Section 3088(a)(3) may be eliminated where spring buffers complying with Section 3088(b)(1)(C) are provided and the speed of the elevator as it approaches the landing is not more than 10 feet per minute and the spring buffers are not compressed under normal operating conditions.

(4) Section 3018. Horizontal clearances shall comply with Section 3055.

(5) Section 3019. Protection of spaces below pits shall conform to the applicable portions of Section 3056.

(b) Machinery and Equipment. The machinery and equipment for elevators with screw type machines shall conform to the requirements of Article 8 except as sections are modified by the following:

(1) Section 3031. (Car buffers)

(A) Spring buffers used on elevators with screw type drive machines shall be so designed and installed that they will not be fully compressed when struck by the car with its rated load at governor tripping speed.

(B) Buffer design shall consider the energy of the rotating machinery and shall provide an average deceleration of not more than 1.0g for oil buffers and a maximum deceleration of 2.0g for spring buffers.

(C) Where recoil of the car upon impact with the spring buffers is detrimental to the screw, dampening shall be provided by means of a hydraulic or pneumatic device to eliminate any recoil.

(D) Calculations satisfactory to the Division shall be provided for each spring buffer design and rating.

(2) Section 3063. (Car frames and platforms) Car frames and platforms shall comply with Section 3063.

(3) Sections 3035 and 3036. Car safeties and overspeed governors. Screw elevators whose screws have not been shown to be capable of supporting 125% of the rated load and the car weight both in compression and tension shall be provided with car safety and overspeed devices of an approved type. Car safeties and governors shall comply with the requirements of Section 3035 for safeties and Section 3036 for governors.

(4) Section 3038. Screw machines shall comply with the requirements of Section 3068, Section 3104 and Section 3038 except subsections (a) and (b).

(A) In the design of screw machines, the load to be used in computing factors of safety shall be the maximum load imposed when lifting 125% of the rated load.

(B) For design purposes, screw machines shall include hoist and pump motors, gear boxes, sprockets, brakes, brake drums or discs, screws, screw supports and fastenings, rotors, lowering mechanisms, pumps, hoses, and other equipment necessary to raise and lower the elevator.

(C) The hoisting screws of screw machines shall have a factor of safety of not less than 15 based on combined tension and torsion stresses when lifting 125% of rated load and combined compression and torsion stresses when the screw is supporting 125% of rated load when used as a column.

(D) Where the rotor or nut travels with the elevator, the machine except for the screw, shall be inaccessible from the elevator car top and from outside the hoistway. Provisions shall be incorporated in the design of such a system for manually lowering the elevator, from the bottom machine room, to gain access to the machine. This manual control shall be failsafe and have a dead-man control. The lowering means shall be adjustable so the lowering speed is less than one-half rated speed with rated load on the car and shall stop and hold a load of 125% of rated load. This adjustment shall be set and sealed at the time of the initial inspection and at periods not exceeding 5 years.

(E) Machines in which the screw is stationary shall have the screw restrained at both the top and bottom ends to prevent the screw from rotating except when the car is being lowered as required by Section 3088(b)(3)(D).

(F) The screw shall be supported vertically and horizontally in such a way as to eliminate those forces or torques not taken into consideration in the design. Factors of safety required by Section 3104 shall be based on loads when lifting 125% of rated load.

(G) Drawings showing details of the entire screw machine and appropriate calculations by a California Registered Engineer shall be provided before the first machine of a kind and rating is installed and when requested by the Division. The calculations shall show the stress in all critical support members and major components of the machine. Where screws are spliced, the details of the splice shall be acceptable to the Division.

(H) The hoist machine brake shall be located so there is no coupling between the brake and screw or rotor.

(I) Belts and chains shall not be used except where multiple-link silent chain is enclosed in a transmission housing. When multiple-link silent chain is used, its wear shall be monitored with a chain switch to remove power from the drive machine motor and brake when chain wear or stretch becomes excessive.

(J) Hoist machine brakes shall be released electrically or hydraulically and applied by springs.

(K) A flexible hose supplying high pressure fluid to the hoisting rotor motor shall comply with requirements of Section 3068(a)(3)(B) except that where the failure of a hose will not result in lowering the car the hose shall have a bursting strength sufficient to withstand only 4 times the working pressure and shall be tested in the factory or in the field prior to installation of a pressure of at least 2 times the working pressure. Flexible hoses shall in addition to other criteria be designed to withstand the flexing to which they are subjected.

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.

HISTORY

1. New Article 12.3 (Section 3088) filed 8-11-83; effective thirtieth day thereafter (Register 83, No. 36).

2. Renumbering of former Article 12.3 (Section 3088) to Article 12.6 and new Article 12.3 (Sections 3085-3085.22) filed 6-9-86; effective thirtieth day thereafter (Register 86, No. 24).

3. Editorial correction of subsection (b)(4)(K) (Register 95, No. 34).

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