Dock Levelers

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Author Message Ralph Liebing, RA, CSI, CDT Senior Member Username: rliebing Post Number: 1101 Registered: 02-2003 Posted on Thursday, November 12, 2009 - 01:34 pm:    We have stumbled into a quagmire regarding what exact loading capacity we can expect from dock levelers. Case in point: Speced 40,000 pounds as Total Gross Weight, but unbeknown to us have found that this is the number when a manufacturer's 2.5 safety factor is imposed; "real" or actual load capacity is about 18,000. Several standards, but in disarray as to defintions and numbers and circumstances [leveler at floor line; at 7% slope to truck bed, etc. How do you specify the loading your client WILL impose [including forklift] on levelers? [the manufacturer can add any fudge factor they choose above this]. Also, reference standard[s] you use. Thanks Mark Gilligan SE, CSI Senior Member Username: mark_gilligan Post Number: 236 Registered: 10-2007 Posted on Thursday, November 12, 2009 - 02:33 pm:    The live loads that are defined in the code are define with the assumption that the structural element will have sufficient capacity to safely carry these loads. Thus if you specified 40,000 pounds and the manufacturer needs a factor of safety of 2.5 the ultimate capacity should be 100,000. Further the term "gross weight" as used in shipping has to do with the weights that can be safely carried. The gross weight capacity of a truck assumes that the truck can safely carry the load with normal factors of safety. I would also assume that this load could supported over the normal operating range of the equipment. My reaction is that the manufacture is trying to game the system. Unless the industry has a clearly defined way that they specify the loading capacity I would believe that live load, gross weight, or operating loads would be clear enough. At a certain point you only create confusion as you try to quality what you mean. No matter what you do individuals can come up with wierd interpretations and when this happens you need to be able to tell them no. Another way would be to find a leveler that can carry the loads you will impose and specify it as the basis of design. Jeffrey Wilson CSI CCS Senior Member Username: wilsonconsulting Post Number: 23 Registered: 03-2006 Posted on Thursday, November 12, 2009 - 03:07 pm:    ANSI MH 30.1 is the governing standard for dock leveling equipment. The appropriate term is "Rated Capacity" which can also be stated as "total gross load." Richard L. Hird (Unregistered Guest) Unregistered guest Posted on Thursday, November 12, 2009 - 08:32 pm:    Jeffrey Underwstand "rated capacity", was wondering how you came to conclusion that "total gross weight" is the same? Is that in MH 30.1? Jeffrey Wilson CSI CCS Senior Member Username: wilsonconsulting Post Number: 24 Registered: 03-2006 Posted on Friday, November 13, 2009 - 09:55 am:    "Total gross load" (not "weight") is used in MasterSpec "Loading Dock Equipment." Upon further review of the Evaluations for this section, it is probably safer to limit references to "Rated Capacity" which is apparently defined in the referenced standard (which I have not read). The Evaluations for this section do warn that "Rated capacity is a controversial issue." There is not complete consensus among dock equipment manufacturers about the methods for calculating this value, although the standard was intended to resolve the controversy and evidently establishes the basis for testing. Though the standard is supposed to make comparison of different products easier, MasterSpec's Evaluations advise that the specifier seek manufacturers' advice for selecting capacities to suit project needs. Ralph Liebing, RA, CSI, CDT Senior Member Username: rliebing Post Number: 1102 Registered: 02-2003 Posted on Friday, November 13, 2009 - 10:12 am:    We are looking at going to the following language for the loading to be carried on the levelers. Have tried to respond to messy standards language and define it our way, so it clear what our clients needs/wants/requires-- without any "adjustments" or hidden agendas on the manufacturers' part; Anticipated Gross Moving Load [Live Material Load plus forklift]: As applied to leveler sloped up to truck bed. Will advise where we come out on this. Ralph Liebing, RA, CSI, CDT Senior Member Username: rliebing Post Number: 1108 Registered: 02-2003 Posted on Friday, December 04, 2009 - 10:21 am:    Update-- we are going to have a meeting over this, but manufacturer told us NOT to spec a specific Model Number, and to note that the TOTAL GROSS LOAD is 16,000 pounds, and that we should note that this is for 5 truck trips per day. Don't ask me why just yet!!!!!! Have data from another manufacturer where TGL is related to range of trucks per day [16,000# is valid? for up to 8 trucks per day] and is increased as number of trucks increases. Is a puzzlement! Hard to understand the relationship because load can vary with trucks and what if there are more trucks than anticipated-- shut the dock down? But a mystery we will solve! Ralph Liebing, RA, CSI, CDT Senior Member Username: rliebing Post Number: 1124 Registered: 02-2003 Posted on Tuesday, January 19, 2010 - 10:57 am:    Finally had our meeting on this issue, The result is that the manufacturer is looking from the following information from us, in order to match levelers with project requirements; A. Capacity: Capable of supporting the following load without permanent deflection or distortion as determined by actual tests in compliance with ANSI MH30.1-2007 (2007) requirements for the capacity of fixed dockboards. 1. Gross Load: _________ pounds. 2. Frequency of Use: ___ trucks/ _____8-hour shifts/day. Gross Load is imposed load plus forklift. Frequency is number of trucks per each 8-hour shift by number of shifts operating per day.