FAQs

Thern has several davit crane models that are appropriate for rooftop applications. Whether you are looking for a rooftop davit crane or a rooftop crane hoist, Thern can offer you long-lift solutions for servicing HVAC equipment or other applications.

Thern offers 20,000 lb winches and 40,000 lb winches. Depending on the speed required and allowable footprint, Thern offers several styles of winches, including 4HS, 4HPF, 4HBP, and 4BP. These winches are offered in a range of voltages and can be powered hydraulically.

Thern offers winches and hoists with capacities up to 100,000 pounds. Our 5,000 lb electric hoists can come in manual spur gear designs, as well as pneumatic and hydraulic. Check out our M452B, M492B, as well as our 4HS, 4HWF, 4HPF, and 4WS models.

Thern offers more than one type of a stainless-steel hand winch with a brake. The M4042PBSS model with a capacity of 1,000 pounds and the M4312PBSS model with a capacity of 2,000 pounds. Both have a frame and drum that are constructed with stainless steel and come standard with an automatic Weston-style brake.

Thern offers a variety of air winches or air-powered winches with capacities up to 37,000 pounds. These air winches can be referred to as pneumatic winches or air tuggers. Check out our Big Red, Mini TA Series, 4771 Series, as well as our C Series. If you’re unable to find what you are looking for, we can design a custom air-powered winch specialized to fit your application.

Thern offers a variety of lifting equipment parts such as wire ropes, hooks, sheaves, headache balls, vertical lead blocks, and other lifting equipment.

Thern offers multiple solutions from material handling lifting equipment to a conveyor belt pulling winch. We even provide a railcar moving winch. We can design a solution specific to your application. The engineering team at Thern can customize virtually any winch in our lineup to accommodate specific speed and control requirements. We can also accommodate site-specific variables such as grade, curvature, and distance. See our online portfolio for some of the most challenging and unique applications we’ve solved for our customers.

Thern offers a variety of lifting solutions that meet ATEX requirements for explosive atmospheres. Just tell us the hazard class/environment the hoist, winch, and controls will be exposed to, and we can design an explosion-proof hoist or system to accommodate it.

Thern offers much more than just wall-mounted electric winches. Many of Thern’s portable and fixed-mount winches are suitable for mounting in different orientations, including floor, wall, and ceiling.

Thern manufactures a variety of compact hand winches and vertical-lift hand winches suitable for both vertical lifting and horizontal pulling applications. These include both spur gear and worm gear models that accommodate a variety of distance and load requirements. Thern also offers a hand winch that can be drill driven.

Several of Thern’s standard crane models can be used as a small vehicle-mounted crane. Additionally, Thern’s Workmate, a hitch-mount davit crane base, was specially designed to be compatible with a standard 2” receiver hitch. The Workmate allows customers to have a crane attachment for a truck, and it can be situated on the ground behind or to the side of the associated vehicle.

Thern provides winches for a variety of mining applications. Mine winches can take on several tasks from MRO to cart pulling to conveyor take-up and tensioning. Some of our customers utilize our products for drag lines and dredging, while others will use them for shaft sinking and plumb bobs.

The difference between an electric hoist and an electric winch is that a hoist refers to a pulling device that lifts vertically with a wire rope or chain. Many people think of a winch as a device that pulls horizontally, when in fact, Thern winches can be placed in virtually any orientation (floor mounted, wall mounted, or underhung) and can pull both horizontally and vertically when properly equipped. Electric hoists will require an automatic brake for vertical lifting applications, while winches for horizontal pulls would not necessarily require a brake. Please reach out to our sales staff to discuss your project and the best solution to fit your needs.

If the weight, height, and reach requirements fit within a Thern davit crane capacity, a davit crane will be easier to install, operate, maintain, and is generally more affordable. Additionally, many of Thern’s davit cranes are more portable than a motorized jib crane. If you buy numerous bases, you can move the cranes to different locations to solve multiple lifting applications with just one crane.

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A gantry crane and davit crane often serve very different functions, but there are times that a davit can serve the same function when equipped with a rolling base.

An aluminum davit crane, while lightweight and corrosion resistant in some environments, sacrifices a significant amount of lifting capacity due to the physical properties of aluminum. A stainless-steel davit crane, while somewhat heavier, provides the ultimate solution in corrosion resistance and lifting capacity.

Fleet angle is the angle between the wire rope and an imaginary line extending perpendicular to the drum. The fleet angle varies with the distance between the lead sheave and the drum. Using the correct fleet angle of wire rope will ensure your winch is operating at its full capacity and not causing undue wear.

In addition to all winch safety, which includes air winch safety, best practices are to:

• Read the owner’s manual
• Make sure the winch is securely mounted
• Make sure supply lines are in good shape and are secure
• Make sure the FRL is installed and in good shape
• Install mufflers to reduce sound level. Mufflers with a filter element can be installed to reduce oil misting for the motor lubrication.
• Install a shutoff valve
• Use controls with an estop if the shut off valve is not within reach of the operator
• Install a drum guard

With manual lifting equipment (such as a hand winch) the work is being done by the operator that is turning the handle of the winch. With electric lifting equipment, the electric motor does the work to turn the drum and spool the lifting rope. Thern offers a variety of both electric and manual lifting equipment.

An air tugger winch is powered pneumatically and designed for maritime use. An electric tugger winch is powered by electricity. If the load is higher or needs to move at faster speeds, then an electric winch may be better suited for the job.

A portable davit crane is designed so that it can be easily disassembled and moved to a different location and reassembled for lifting operations. Generally, stationary davit cranes offer the benefit of longer reach over a portable davit crane of comparable capacity. Thern offers a variety of both portable and stationary davit cranes with different lifting capacities.

An electric davit hoist requires an electrical input and uses an electric motor to turn the drum spooling the wire rope. A hydraulic hoist requires pressurized hydraulic fluid (typically from a hydraulic power unit) as input for a hydraulic motor, which turns the winch drum to spool the wire rope.

Service parts can be obtained directly from the Thern factory by contacting Thern Customer Service at 800-843-7648.

Please contact the Thern Customer Service Department at 800-843-7648 with all repair and service inquiries. Our Customer Service Representatives will determine the best course of action to be taken to repair your winch or crane.

All Thern products carry a two-year limited warranty. Thern, Inc. warrants its products against defects in material or workmanship for two years from the original date of purchase.

The importance of underwound compared to overwound wire rope depends on the winch being used, and it is most important when a brake is incorporated into the winch. Hand winches with disc brakes only hold the load in one direction. The same holds true for the internal brakes used on 477 and 4WP2 series power winches as well as the band brake on TA Series air winches. This means that running any of these winches with the wire rope wound incorrectly will cause the winch to work against the brake. This could cause the brake to function improperly which could allow the load to fall. It will also cause premature wear on the brakes. Prolonged use of overwound wire rope on Series 477 power winches will also cause internal failure to the reducer (gearbox), and the frame of a hand winches will flex far less with underwound wire rope.

Click here for a complete explanation.

Due to the substantial amount of difference between the components used in these two styles of spur gear hand winches, it is not cost effective to do this type of conversion.

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The reducer on the 4WP2 Series holds 44 oz. of Mobilgear 630 or Mobilgear 600 XP 220 gear oil.

The reducer on the 477 Series holds 92 oz. of Mobilgear 630 or Mobilgear 600 XP 220 gear oil.

Click here to view the reducer lubrication information.

Click here to view the reducer lubrication information.

Click here to view the reducer lubrication information.

Please consult with Thern, Inc. for approval before attempting this conversion. Any conversion attempted without Thern’s approval will alter the finished product from its original design and could void the warranty.

Click here for complete instructions.

Click here for complete instructions.

Click here to view the reducer lubrication table.

Click here to view the motor lubrication table.

Nearly all failures reported with this symptom have failed due to the wire rope being overwound rather than underwound. Overwinding the wire rope forces the worm shaft in the reducer up into the bottom of the motor adapter plate, and over time the large helical gear on top of the worm gear wears into the adapter plate. This misalignment will cause premature failure of the upper bearing and other related components.