China two crank manual hospital bed with casters supplier: Specification, Ordering and Quality Notes

Scope of Supply and Physical Form

Replacement rate, not unit price, drives the real cost of a two‑crank manual bed program. A bed that drifts 5 mm in overall length across lots forces a re‑work of mattress fit and adds freight claims. The specification below locks the critical envelope so the buyer can price total cost of ownership before the first container ships.

Design Constraints Behind the Specification

The two‑crank layout is chosen because a single crank would require 50 % more operator force at the same height increment, pushing the effort beyond the 150 N ergonomic limit for nursing staff. Caster lock engagement must withstand a 200 N lateral push without disengaging, otherwise the bed migrates during patient transfer. Frame welds are spaced at 250 mm centers to keep deflection under 2 mm under full load, and the powder coat thickness is controlled to 80 ±10 µm to avoid chipping at the crank mounting points.

The double‑crank architecture adds two extra bearing housings, which increases the bill of materials by roughly 3 % but reduces the peak handle torque from 22 Nm to 12 Nm, a trade‑off that pays back in reduced staff fatigue over a 5‑year service horizon.

Assumptions Buyers Should Stop Making

Buyers often assume that all casters from the same supplier share identical swivel torque, yet a 0.5 Nm drift between lots changes the push force needed to move a loaded bed by 15 %. Another assumption is that the crank handle length is fixed; in practice a 10 mm variation alters the mechanical advantage enough to shift the torque curve. Finish colour is also treated as a cosmetic detail, but a 2 ΔE shift between batches triggers rejection in private‑label programs that require visual consistency across wards.

• Caster swivel torque is not guaranteed across production runs.
• Crank handle length can vary ±10 mm unless a dedicated fixture is specified.
• Powder‑coat hue drifts up to 2 ΔE without a colour‑master agreement.
• Bed frame length tolerance of ±3 mm may not match mattress spec of ±2 mm.

What Gets Checked Before Shipment

Every lot passes a fixed inspection sequence before the container is sealed. The table summarises the test, the acceptance window, and the consequence of a fail.

Stock Availability and Reorder Planning

Lot‑to‑lot consistency is the single biggest driver of reorder friction. A 2 mm shift in frame length across two consecutive productions forces the buyer to re‑qualify mattress suppliers and update warehouse slotting. The factory holds a rolling buffer of 200 units for the standard 2150 mm length, but custom lengths require a 30‑day tooling lead time and a minimum order of 50 units.

Reorder cycles of 8 weeks are typical when the buffer is intact; extend to 12 weeks if a new fixture is needed. Plan safety stock at 1.5× the monthly consumption to absorb the variability.