At a glance
| Patent number | CN105805510B (application CN201610295579) |
| Type | China invention patent (发明专利) - protects product shape, structure and method |
| Original title | A kind of instrument of surveying and mapping tripod (一种测绘仪器三脚架) |
| Patent owner | Individual (Wang Yuzhen) |
| Inventors | Wang Yuzhen, Song Rongfang, Zhang Dongling, Zhang Jian |
| Filing date | 2016-05-06 |
| Grant date | 2017-08-25 |
| Status (China) | Lapsed - terminated for non-payment of annual fees (recorded 2019-04-19) |
| Patent family | Chinese filings only - no US, European, Japanese, PCT or other filings listed |
| Cited by | 3 later documents |
| Source | Google Patents (search for CN105805510B) |
What the claims cover, in plain language
Claim 1 - a surveying tripod comprising an instrument fixed seat, an adjustment seat and three supporting legs. The seat has a circular fixing groove centered on it, with a bubble and scale embedded beside the groove. Three lock-screws thread inward from the sides, each tipped with an arc spacer. A vertical adjusting rod fixed to the seat’s underside slides coaxially into the adjustment seat, locked by a fastening bolt. A hook is centered on the adjustment seat’s bottom surface. Each leg hinges to the seat and ends in a retractive leg section. A micro-adjusting mechanism on each leg includes a transmission case and an adjusting screw rod riding in a guide groove. Inside the case, a bushing threaded onto the screw is supported by two thrust bearings and carries a first bevel gear keyed to it. A horizontal rotating shaft on a mounting seat holds a second bevel gear meshing with the first and ends in a regulation handle protruding through the leg. The screw’s bottom extends into the retractive leg and connects via a thrust bearing. The retractive leg contains a telescopic cavity with a sliding expansion link clamped by a clamping screw. The link’s lower end carries a support foot made of a support base and a fixed pin, with a bulb fixed to the expansion link by studs and hinged on the support base.
Claim 2 - the bubble and scale is spherical, covered by a round glass panel bearing three principal mark lines intersecting at the center (each aligned with one leg) and several concentric secondary graticules. Claim 3 - the hook suspends a load-carrying disk or a plummet by a bracing wire. Claim 4 - the fixed pin is either a cone nail or a rubber cushion block.
This is a simplified reading for orientation only. The legal scope is defined by the exact claim wording in the official Chinese document.
What this means for US production
This patent was filed only in China and is lapsed due to non-payment of annual fees, so it no longer restricts anyone in China either. It has no US or other foreign counterpart.
Two points to settle early:
- Other patents may exist. Surveying tripod leveling mechanisms, including geared leg adjustments and specialized bubble scales, are patented by major surveying equipment manufacturers in the US and Europe, so a freedom-to-operate (FTO) review of the bevel-gear drive and the radial bubble scale layout is needed before tooling.
- Load capacity and materials. Leg tube diameter, wall thickness, gear module and screw pitch must be engineered for the intended instrument weight (e.g., lightweight levels vs. heavy total stations).
Customization and manufacturing
What can be customized
| Area | Options |
|---|---|
| Leg material | Aluminum alloy extrusion, fiberglass composite, or wood (ash or mahogany) |
| Leg profile | Round tube, flat strip, or box section depending on stiffness targets |
| Extended height | To be confirmed in design based on target instrument eye-height |
| Collapsed length | Set by retractive leg stroke and transmission case placement |
| Gear ratio | Bevel gear tooth count adjusted for finer or faster micro-travel per handle turn |
| Foot options | Interchangeable spikes, carbide tips, or rubber pads |
| Instrument seat | Flat-top with standard 5/8"-11 thread insert instead of, or in addition to, the arc-spacer groove |
| Finish | Anodized, powder-coated, or painted legs; plated or stainless hardware |
Things to plan for (US market)
- General product safety - tripods are professional tools without a specific CPSC consumer standard, but sharp edges, pinch points at hinges, and structural integrity fall under general duty-of-care expectations.
- California Proposition 65 - brass gears, plated screws and certain paints may contain lead or cadmium requiring warning labels if sold in California.
- Material testing - aluminum alloys should meet ASTM specifications for structural tubing; fiberglass legs may need UV-resistance verification for prolonged outdoor use.
How a project runs
- Inquiry - target instrument weight class, preferred leg material, extended/collapsed dimensions and quantity.
- Design - engineering drawings for the transmission case, bevel gear set, screw pitch, hinge geometry and seat interface.
- Prototype - CNC-machined samples of the gear housing and screw assembly assembled onto extruded or turned legs for functional testing.
- Pilot run - load testing with representative instruments, cycle testing of the micro-adjustment mechanism, and corrosion checks on finishes.
- Production - die casting or machining of gear housings, hobbing of bevel gears, thread rolling for adjusting screws, leg extrusion or woodworking, anodizing or coating, and final assembly.
Quantities & timeline
The bevel gears and threaded adjusting screws require dedicated hobbing and thread-rolling tooling, while the transmission cases typically need die-casting molds or multi-axis CNC fixtures. Leg profiles require extrusion dies or woodworking jigs. Load certification tests take additional lead time. Send us your target instrument weight, leg material preference, dimensional requirements, estimated quantity and target price and we will reply with options.
Patent drawings
Drawings reproduced from the public patent document for reference.
