Thern Davit Crane Parts

Thern Davit Crane Acessories Buying Guide

Bases first: match the mount to the crane, not the other way around. The base is the single most-ordered part on this page and the easiest to get wrong, because Thern cuts them per series. A base built for the 5PF5, 5PT5, and 5PA5 portables will not accept a 5PT20 boom, and a 5PT30 transportable base is a different part again. Order by the model number stamped on your crane, the same string that runs through these titles: 5PF5/5PT5/5PA5, 5PA10/5PT10, 5PT20, 5PT30, and the aluminum 5AT series. Get the series right and the mounting style is the next decision. Prices track size, so a socket base for the 5PF5 group starts around $207 while a 5PT30 socket runs past $1,300.

Socket, pedestal, or wall-mount. Thern builds three mounting styles and each puts the base in a different place. A socket base sets flush into a floor or a structure so the deck stays clear when the crane lifts out, which is the right call for walkways, docks, and anywhere foot traffic crosses the spot. A pedestal base, also called an upright mount, bolts to the surface and stands the crane up off the floor, the simplest install where a raised base is not in the way. A wall or side mount hangs the crane off vertical steel or concrete when there is no floor to give up. One tradeoff worth knowing: a socket mount alone lowers your maximum hook height, and a base extension, from about $355 for the 5PA10/5PT10, restores that height without touching the crane's load rating. Every base comes in powder-coated, galvanized, or 304 stainless, so match the finish to the environment.

Wire rope assemblies: galvanized or stainless, sized to the winch. The rope is a wear part, and this page carries pre-made, swaged assemblies rather than bulk spool so the end fitting is rated and ready to reeve. Two choices decide it. Diameter has to match the winch and the crane's capacity: stock runs 3/16, 1/4, 5/16, and 3/8 inch, and thicker rope means more load and more drum. Coating settles the rest. Galvanized rope, from about $148, is the general-industrial choice for indoor and outdoor work where moisture is limited. Stainless, from about $251, is what you buy for marine, coastal, and chemical settings where a galvanized coating would wear through and rust. Buy the diameter Thern specs for your crane, not the heaviest rope that happens to fit the drum.

Powering the winch: hand, drill, or full power unit. A davit's winch is where the lift actually happens, and this page covers all three ways to turn it. An M2 worm-gear hand winch is standard on the smaller cranes; a Dewalt drill drive kit, from about $1,070, clamps to that same winch and spins it under cordless power for crews cranking dozens of lifts a shift. When the duty cycle justifies it, a limit-switch-ready power winch, roughly $410 to $11,490 depending on line pull, replaces the hand unit entirely, and the matching 12-volt limit switch, from $2,250, stops the drum automatically at the top and bottom of travel so nobody two-blocks the hook. Spec the winch to how often the crane runs, not the one-off worst case.

Rope hardware that keeps the line behaving. A few small parts do outsized work on a single-line davit. A headache ball, from about $240, hangs a weight below the hook to keep tension on the whip line so it spools clean on the drum instead of birdcaging when the hook runs empty. A vertical lead block, rated to 7,000 lb, redirects the wire rope around a corner or down a shaft when the pull is not a straight line off the drum. A cable spooler, at $484, winds rope on and off without kinks, and a wire rope keeper, from $39, holds the dead tail in place. None of these are optional if you want the rope to last through its rated cycles.

Finishing the install: anchors, locks, and covers. Two more part groups close out a job. Base fastener anchor kits, Hilti pattern from $45, supply the rated anchors that fix a pedestal or socket base into concrete to Thern's drawings, so the base is only as strong as what holds it down. A rotational lock, from $233 for the 5PA5/5PF5/5PT5 group, pins the boom against swinging when a lift needs to stay put, and a roller ball bearing at $600 smooths rotation on the 5PT20. Replacement protection covers with a lanyard, from $51, cap an empty socket so it does not fill with debris between lifts. Small line items, but they are the difference between a base that lasts and one that seizes.