UMS QUESTIONS - 2.pdf

FA8533-08-R-10163

UNIVERSAL MAINTENANCE STAND

9 APRIL 2008

1) Current Generation UMS

A) Can we use portions of the previous design and consider them adequate, or does everything have to be re-certified for structural integrity and mobility properties? Example:

can the existing scissor design be used without recalculating stresses as long as the platform weight plus the capacity is equal to or less than the previous generation?

ANSWER: This design effort will result in a new drawing package and TO. All design information will have to be submitted as a new effort.

B) In the testing sections of the purchase description (P.D.) what does “tests may be waived after review and acceptance of manufacturer’s certification” entail?

ANSWER: The environmental tests (section 4.6.5 and subsequent subsections) may be waived. The government is willing to review previous builds certifications of testing if the material is the same as on this new design effort.

2) Section 3.2 Chassis/frame

A) The P.D. states that the UMS shall be a “split deck four wheel” design to effectively facilitate movement. If this is the chassis/frame section, what is “split deck” referring to?

ANSWER: The split deck is referenced to the platform style.

B) The P.D. states that the frame shall be constructed of corrosive resistant materials.

Are you talking about the chassis (which the wheels are mounted to) or the frame of the platform? The previous sentence makes this confusing.

C) If you are addressing the chassis, is steel not permitted on this unit? (Also see item 4.)

3) Section 3.5 Deck surface A) You want the floor material to be mild enough that you could kneel or lay down on it.

Have you considered the open-grip type flooring that you had on previous UMS contracts to be mild enough to kneel on? It is our experience that non-slip coatings wear off or degrade, compromising the traction.

ANSWER: Anti-skid flooring could be from coating or from type (example: open-grip).

4) Section 3.7 Non-corrosive materials A) Is an aluminum platform acceptable or preferred?

B) We want to specify the base and scissor to be built of steel due the need for stabilizing weight and structural integrity. Is this acceptable?

ANSWER: (A and B will be answered together.) This is the contractor's design. If something is not specified in the PD it is left to the contractor's discretion.

ANSWER: (B and C will be answered together.) The entire unit should be constructed on corrosive resistant materials to the maximum extent possible. If a material is used that could corrode then it should be treated to be resistant to corrosion.

9 APRIL 2008

A) –40 to 130 F is an extremely harsh range of temperatures, which will add substantial cost to the unit, provided the components are available. Rated storage temperatures of –65 to 160 F will be even more difficult to find on component ratings. We have provided similar products for the government that require operation ranges of –25 to 125 F, and storage ranges of –40 to 140F. Would these ranges be considered?

ANSWER: The AF environmental requirements are as stated by the PD.

6) Section 3.13 Prime movers A) The P.D. states “…batteries charged by an electric motor…”. Is this referring to regenerative braking, where the drive motor reverses direction and returns voltage to the battery during braking, or should this phrase have been “…batteries powering an electric motor…”?

ANSWER: The AF requirement is for the UMS to be powered by either the diesel engine or by batteries (the batteries will use an electric motor to keep them charged) B) Will the diesel engine ever be utilized in the Group D environment, or is this the intent for adding the “electric engine” capability?

ANSWER: The batteries will power the UMS when in group D atmospheres and class I, division 2 hazardous locations.

C) For the “electric engine” operation, was this intended to be a DC motor supplied by on-board batteries or is it intended to be an AC motor supplied by wall outlet power (electrical utility)?

ANSWER: The contractor will need to determine style of electric motor.

D) Based on whether the motor is to be DC or AC, the battery & charging requirements need to be clarified (battery types, charging modes, input voltages, etc).

ANSWER: This unit will be the contractor's design. The contractor will need to state what will be required.

E) Are the Group D type classifications related to system components or does the UMS as a complete unit require the classifications?

ANSWER: The UMS has requirements to be used in group D atmospheres and class I, division 2 hazardous locations.

F) Based on motor type, battery type, and intended usage within Group D environments, the type classification(s) need to be clarified. More than one type is acceptable in such environments (ES and EE for electric-powered equipment, DS and DY for diesel-powered).

ANSWER: The UMS has requirements to be used in group D atmospheres and class I, division 2 hazardous locations and should be powered by the batteries.

G) Based on which type(s) of equipment is required, is UL certification and marking (serialized metal legend plate) required to authenticate that all requirements of the type have been satisfied?

ANSWER: It is left to the contractor's discretion on how to prove equipment meets government requirements.

7) Section 4.6.8 Platform load test A) Is the machine required to change elevation under this load of four (4) times the maximum capacity?

9 APRIL 2008

ANSWER: The Load Test will be tested in a static state of the UMS.

B) If the load can be applied to the platform and remain static, should it be applied at any particular height?

ANSWER: The Load Test will be tested in both a retracted and extended state of the scissors.

C) The P.D. requires compliance to ANSI A92.6. This spec requires a proof load test of 150% of the rated load during which the unit is fully operated. Failure results from any visible permanent deformations. It also requires a design safety factor of 2.75, which includes dynamic and stress concentration factors. If we were to perform the proof load test at four (4) times the capacity rating, then we will need to have a design safety factor of about 8.00 just to make the test safe. We expect that the overall design will be excessive relative to ANSI and industry standards and will compromise the cost, weight, and efficiencies of the UMS. Why is the proof load requirement so much greater than ANSI and industry standards?

ANSWER: The government requires the platform be designed to have a safety factor of 4 (four times the Maximum Platform Load (2000 lbs)).

9 APRIL 2008Answers